Timing matters in the Thousand Islands. Most major attractions — castles, boat tours, museums — operate seasonally, so when you go shapes what you'll be able to do.
Summer (Late June – August) is peak season, and for good reason. Temperatures hover around 80°F, towns like Alexandria Bay and Clayton buzz with activity, and the St. Lawrence is alive with boat traffic. It's the ideal time for swimming and time on the water, with events like the 4th of July celebrations and Seaway Splash — a dock-jumping contest for dogs — adding to the festive atmosphere. July is the busiest month, so expect crowds.
Late Spring and Early June offer a quieter alternative. The landscape is lush and blooming, the towns are uncrowded, and most major attractions — including Boldt Castle and the Antique Boat Museum — typically open by mid-May. It's a good window for travelers who want the full experience without the summer rush.
Autumn (September – October) is perhaps the most underrated time to visit. September brings clear skies and low humidity, with water still warm enough for swimming. By October, the region's foliage is in full color — Alexandria Bay is frequently cited as one of the top towns in the Northeast for fall viewing — and the St. Lawrence enters its prime season for muskie fishing.
Flying into the Region
Most travelers fly into a nearby airport and rent a car for the drive to the riverfront. The closest option with commercial service is Watertown International Airport (ART), about 40 minutes from Alexandria Bay, served by American Airlines connections. For more flight choices and rental car availability, Syracuse Hancock International Airport (SYR) is the region's major hub — about 90 minutes south, but worth the extra drive. A lesser-known alternative, Ogdensburg International Airport (OGS), sits roughly 50 minutes northeast of Alexandria Bay and is a convenient gateway for travelers arriving from Canada. Travelers coming through Canada may also consider Ottawa Macdonald-Cartier International Airport (YOW), about an hour and 45 minutes away.
Driving and Border Crossings
The region is straightforward to reach by car. Interstate 81 runs directly north through the heart of the islands and serves as the main corridor between the U.S. and Canada. The Thousand Islands Bridge spans the St. Lawrence River, linking Alexandria Bay, NY, to Lansdowne, Ontario — the primary crossing for motorists in the area. Once you've arrived, Route 12 and Route 12E offer scenic drives along the coastline, winding through the major waterfront villages.
Getting Around the Islands
With more than 1,800 islands in the region, many destinations are only reachable by water. Tour boat companies like Uncle Sam Boat Tours in Alexandria Bay and Clayton Island Tours are the go-to option for visiting landmarks such as Boldt Castle on Heart Island. For access to private islands or rental properties, water taxis are available on demand.
It depends on where you stay and which boat tours you choose. Because the Thousand Islands straddles the U.S.-Canada border, you can have a complete vacation without ever needing a passport — but the moment you cross into Ontario, either by road or by boat, you'll need one.
When you don't need a passport
If you're staying on the U.S. side — in towns like Alexandria Bay, Clayton, or Cape Vincent — and keeping your activities to American waters, no passport is required. This includes most popular boat tours. Operators like Uncle Sam Boat Tours and Clayton Island Tours run "Two Nation" sightseeing cruises that weave through both U.S. and Canadian waters, but as long as the boat doesn't dock in Canada, U.S. citizens can board without a passport. Boldt Castle, despite its setting in the middle of the river, is also U.S. territory — shuttle boats from Alexandria Bay or Clayton get you there without any border formalities.
When you do need a passport
Driving across the Thousand Islands International Bridge into Ontario requires a valid U.S. Passport, Passport Card, or Enhanced Driver's License (EDL) — a standard driver's license won't do. The same applies on the water: if your boat tour includes a stop at a Canadian port such as Rockport or Ivy Lea, you'll go through customs and need proper documentation. Travelers based on the Canadian side who want to visit Singer Castle — which sits on the U.S. side of the river — will need to clear U.S. Customs on arrival.
Traveling with children
U.S. citizens under 16 can generally present an original or certified birth certificate in place of a passport for land and sea crossings. Adults must carry a WHTI-compliant document: a Passport, Passport Card, EDL, or NEXUS card.
One practical tip: If you have a NEXUS card, use it. The Thousand Islands Bridge has dedicated NEXUS lanes, and during busy summer weekends, regular border wait times can stretch to two hours.
The Thousand Islands is a chain of 1,864 islands scattered across the St. Lawrence River where it flows out of the northeastern corner of Lake Ontario — and it belongs to two countries. The international border runs right through the middle of the river, dividing the islands between New York State and Ontario. To keep things tidy, the boundary zigzags to ensure each island falls entirely within one nation or the other.
On the U.S. side, the principal towns are Alexandria Bay, Clayton, and Cape Vincent, home to landmarks like Boldt Castle and Singer Castle.
Across the river, the Canadian side takes in Gananoque, Rockport, Brockville, and the city of Kingston, much of which falls within Thousand Islands National Park — Canada's oldest national park east of the Rockies.
Not every rock poking out of the St. Lawrence qualifies. To be officially counted among the 1,864 islands of the archipelago, a piece of land must stay above water year-round, measure larger than one square foot, and support at least two living trees. Anything that falls short — too small, too bare, or submerged during the spring runoff — is classified as a shoal. Local captains treat these distinctions seriously: thousands of uncounted rocks lurk just below the surface, shallow enough to shear a propeller clean off.
The islands themselves range dramatically in scale. Wolfe Island, sitting entirely within Ontario, is the largest in the chain — roughly 20 miles long and 7 miles wide, with its own town, working farms, and a wind turbine farm spread across its interior. At the opposite extreme is Just Room Enough Island, the smallest inhabited speck in the archipelago. It holds exactly one house, one tree, and two shrubs; step off the porch and you're essentially in the river.
Ownership is equally varied. Many islands are privately held, ranging from modest summer cottages to grand Gilded Age estates. Others are managed by the New York State Office of Parks or Parks Canada, keeping them open to the public for camping and hiking.
In all, the islands stretch roughly 50 miles along the St. Lawrence. The name "Thousand Islands" might sound like a tourism tagline, but the actual count of 1,864 suggests the region quietly under-promised and over-delivered.
Boldt Castle sits on Heart Island in the middle of the St. Lawrence River, so the only way to reach it is by boat. Most visitors depart from the mainland — either the New York or Ontario shore — using one of several tour operators.
From New York (no passport required)
Because Heart Island is U.S. territory, travelers arriving from the American side don't need to clear customs. The two main departure points are Alexandria Bay and Clayton. Uncle Sam Boat Tours, based in Alexandria Bay, runs a dedicated castle shuttle every 30 minutes during peak season — you can board directly or pair it with a longer sightseeing cruise first. Clayton Island Tours, operating out of Clayton, offers a more scenic route with narration covering local history and the Gilded Age estates along the way.
From Canada (passport required)
Crossing from Ontario means crossing an international border, so bring a valid passport or Enhanced Driver's License. You'll clear U.S. Customs and Border Protection upon arrival at Heart Island. Gananoque Boat Line departs from Gananoque with large excursion boats that stop at the castle. Rockport Boat Line, launching from Rockport, Ontario, is the closest Canadian departure point and offers the shortest transit time to Heart Island.
The Yacht House
Castle admission typically includes access to the Boldt Castle Yacht House on nearby Wellesley Island. A free mahogany shuttle runs between the two islands. Inside, you'll find a collection of antique wooden boats and George Boldt's original 128-foot yacht, the La Duchesse.
Arriving by private boat
Heart Island offers public dockage on a first-come, first-served basis for a fee. Private boaters arriving from Canada must still report to the U.S. Customs station located at the island dock.
Plan on 2 to 3 hours for the castle alone, or closer to 3 to 4 hours if you add the Yacht House — which is worth it if you have the time.
The main castle on Heart Island takes most visitors around 90 minutes at a comfortable pace. That covers six floors of self-guided interior rooms, the Italian Garden, the Alster Tower (known as the Playhouse), and the Power House. Rushing through in less than that is possible, but you'll likely feel like you missed something.
The Yacht House on Wellesley Island adds another 45 to 60 minutes, plus a short shuttle ride between the two islands. If antique wooden boats and Gilded Age maritime history appeal to you, it's an easy addition.
A few logistics worth keeping in mind: shuttle boats from Alexandria Bay take only 10 to 15 minutes, but if you're on an organized "Two Nation" tour, expect 1 to 2 hours of river sightseeing before the castle stop. Once on the island, the experience is entirely self-guided and unhurried — you can linger as long as you like until the last shuttle of the day, which typically departs around 6:30 PM during the main season. On peak summer weekends in July and August, there may be short waits at the admission booth or for the Yacht House shuttle, but lines move quickly.
Renting your own boat is one of the best ways to explore the region — and there's no shortage of options depending on your group size and what you're after.
Where to rent
Most rental operations are based in the main river towns. In Alexandria Bay, TI River Rentals (Aqua-Mania) is the largest provider, with a fleet ranging from smaller bowriders to 13-person tritoons. In Clayton, both Clayton Marina and Bayside Marina offer powerboats and fishing boats. On the Canadian side, Peck's Marina near Ivy Lea and Gilbert Marine in Gananoque are reliable options for motorboats.
Requirements
New York State requires a boater safety certificate to rent a motorboat — the marina will walk you through a safety orientation before you head out. Most locations require renters to be at least 18 (sometimes 21), and expect a credit card authorization for a security deposit. Children under 12 must wear a life jacket whenever the boat is moving.
A few things to know before you go
Fuel is almost never included in the rental price — you'll start with a full tank and pay for what you use on return. More importantly, the St. Lawrence is full of shoals: rocks sitting just inches below the surface that can cause serious damage. Rental boats are equipped with GPS or chart plotters, and staying within marked navigation channels isn't optional — it's essential.
Houseboats
For something more immersive, 1000 Islands Houseboat Rentals operates on the Canadian side and lets you cruise and sleep on the river. It's a popular way to work through the national park islands that offer public dockage.
The Thousand Islands has a legitimate claim to being one of the premier freshwater fishing destinations in North America, offering everything from hard-fighting trophy predators to abundant panfish that are perfect for beginners and kids. Because the region straddles the border, make sure you're fishing with the correct license — New York or Ontario — for whichever side of the river you're on.
What you can catch
Smallmouth Bass — The region's signature species: high in numbers, aggressive on the take, and renowned for their fighting strength. Season runs June 15 through November 30, with catch-and-release permitted earlier in the year. Target rocky structures and drop-offs where depth changes quickly; the waters near Carleton and Grindstone Island are legendary among locals.
Northern Pike — Aggressive predators drawn to weedy bays, open from May 1 through mid-March. Best known for fast, hard action rather than finesse.
Walleye — Also open May 1 through mid-March, and prized above all for the table. Few freshwater fish match them for flavor. Look for them near bridge pilings and deep shoals.
Muskellunge (Muskie) — The fish of 10,000 casts. The St. Lawrence grows them past 50 inches, and the season runs June 1 through November 30. Fall is peak season, but these fish require heavy-duty specialized gear and an intimate knowledge of the river's deep holes — hiring a local charter captain is strongly recommended.
Largemouth Bass — Prefer slower, shallower water than their smallmouth cousins. Focus on weedy bays like the Lake of the Isles on Wellesley Island.
Yellow Perch, Sunfish & Crappie — Available year-round and catchable off almost any town dock on a simple worm or small jig. The easiest entry point for new anglers, and reliably good eating.
You won't find whale watching or dolphin tours in the Thousand Islands. The region is a freshwater environment, and whales and dolphins are marine mammals that depend on the saltwater, depth, and food sources found much further downstream.
What you will find here is rich freshwater wildlife — Great Blue Herons, Osprey, Bald Eagles, various turtles, and beneath the surface, shipwrecks and fish like muskie and smallmouth bass visible on glass-bottom boat tours out of Clayton.
For whales, you'd need to travel northeast into Quebec, where the St. Lawrence widens, deepens, and turns brackish. The closest world-class whale watching is around Tadoussac and Rivière-du-Loup — roughly a 6 to 7 hour drive from the Thousand Islands — where Belugas, Humpbacks, and even Blue Whales are regularly spotted.
The Thousand Islands spans two countries and offers a remarkable range of experiences — so the best way to see it depends on what kind of traveler you are. Here are the top options, from classic cruises to aerial views.
Guided boat cruises
For first-time visitors, a narrated cruise is the definitive introduction. You'll pass through Millionaire's Row, spot historic lighthouses, and glide by Zavikon Island, home to what's claimed to be the world's shortest international bridge.
From Alexandria Bay and Clayton on the U.S. side, Uncle Sam Boat Tours offers hop-on, hop-off shuttles to Boldt Castle as well as scenic sunset cruises. On the Canadian side, the channels around Gananoque and Rockport are narrower and arguably more scenic — City Cruises Gananoque and Rockport Cruises run everything from quick one-hour highlights to five-hour castle tours. For something more upscale, Kingston 1000 Islands Cruises operates live-music brunch and sunset dinner cruises out of Kingston, Ontario.
One note on passports: you don't need one if your boat simply passes through both U.S. and Canadian waters without docking. You will need valid border documents if your cruise lets you step off in the other country.
Kayaking and island camping
For those who'd rather skip the crowds and find some quiet, getting down to water level changes the experience entirely. Guided sea kayaking trips — such as those offered by 1000 Islands Kayaking in Gananoque — take you through shallow channels in the Admiralty and Navy island groups where larger tour boats can't go.
Thousand Islands National Park, spread across more than 20 islands on the Canadian side, offers docks, hiking trails, primitive campsites, and "oTENTiks" — a comfortable hybrid of cabin and tent — accessible only by water taxi or kayak. It's one of the most distinctive national parks in Canada.
Aerial views
To truly grasp the scale of 1,864 islands winding through the river, you need to see them from above. 1000 Islands Helicopter Tours in Gananoque offers a bird's-eye perspective of the bridges, shipping channels, and castles that's hard to match for sheer drama. If you'd prefer solid ground, the 1000 Islands Tower on Hill Island lifts you 400 feet by elevator for a 360-degree panoramic view right in the middle of the river.
Castle touring
The islands deserve more than a passing glance from the water. Boldt Castle on Heart Island is the region's crown jewel — a 120-room Rhineland-style mansion commissioned by millionaire George Boldt for his wife, abandoned mid-construction after her sudden death, and eventually restored to its current grandeur. Further downriver, Singer Castle on Dark Island takes a different approach: modeled on Scottish architecture, it features hidden panels, secret passageways, and a hand-carved Italian stone fireplace. Unusually, you can book an overnight stay in the castle's royal suite.
Where you base yourself shapes the entire trip. The region offers everything from lively tourist towns to isolated island retreats — and your first decision is which side of the border to be on.
Alexandria Bay, NY — best for activity and castle access
"A-Bay" is the bustling hub of the American side, packed with restaurants, bars, souvenir shops, and marinas. It has the classic energy of a summer resort town, and Boldt Castle is a short boat ride away. The Riveredge Resort is the top upscale pick, with Castle View rooms and private balconies looking directly across the river at Heart Island. For a livelier atmosphere, Bonnie Castle Resort & Marina is a historic property with an on-site marina and a bar and restaurant scene that stays active all summer.
Clayton, NY — best for a quieter, boutique experience
Fifteen minutes downriver from A-Bay, Clayton trades the hustle for a more refined pace. It's walkable, artsy, and anchored by local breweries and the Antique Boat Museum. The 1000 Islands Harbor Hotel, a AAA Four-Diamond property on the river's edge, is the standout option — modern luxury with fire pits overlooking the water and excellent dining on site. It's a natural fit for couples or anyone after a more relaxed stay.
Gananoque, ON — best all-around base on the Canadian side
Known as the Gateway to the Thousand Islands, Gananoque balances local culture, outdoor access, and waterfront charm better than anywhere else in the region. The Gananoque Inn & Spa, a historic brick-and-beam inn originally built as a carriage works in the 1860s, sits right on the riverbank and is within walking distance of the Thousand Islands Playhouse theater. For a clean, modern, budget-friendly alternative, Tru by Hilton Gananoque is consistently well-rated. Gananoque is especially well-positioned for kayakers, hikers, and families using the Canadian boat cruises or exploring Thousand Islands National Park.
Kingston, ON — best for a city base with history and culture
At the junction of the St. Lawrence and Lake Ontario, Kingston is a handsome limestone city — Canada's first capital — with a serious culinary and cultural scene. It's further from the dense island cluster, but it more than compensates with museums, restaurants, and landmarks like Fort Henry and the Kingston Penitentiary. Whitney Manor, a beautifully restored 200-year-old limestone mansion a few minutes outside downtown, is the top boutique option.
On the water — for something unforgettable
If the mainland feels too ordinary, skip it entirely. The royal suite at Singer Castle on Dark Island can be booked for an overnight stay — you get the run of the castle after public tours close, including a private catered dinner. For something wilder, rent a waterfront cabin or an oTENTik on one of the granite islands within Thousand Islands National Park. You'll arrive by kayak or water taxi and sleep under open skies surrounded by the St. Lawrence.
The region is anchored by a string of historic waterfront towns and villages strung along both sides of the St. Lawrence River and the eastern edge of Lake Ontario. Each has its own character.
On the U.S. Side (New York)
Alexandria Bay — The main tourist hub on the American side, and the most energetic. Bars, boat tour docks, and souvenir shops line the waterfront, and Boldt Castle sits directly across the water.
Clayton — A walkable, slightly more refined village about 15 minutes downriver. Clayton is known for its artisan shops, craft breweries, and the world-class Antique Boat Museum.
Cape Vincent — Sitting at the exact point where Lake Ontario ends and the St. Lawrence begins, Cape Vincent is quieter and more unhurried. It's best known for the historic Tibbetts Point Lighthouse and strong sport fishing.
Sackets Harbor — A bit further south along Lake Ontario, Sackets Harbor is a beautifully preserved lakeside village with deep roots in the War of 1812. It has a historic battlefield, boutique inns, and intimate dining.
Thousand Island Park (Wellesley Island) — Less a town than a Victorian time capsule. Founded in 1875 as a cottage community, it's a dense cluster of brightly colored gingerbread-style homes that feels entirely removed from the present day.
On the Canadian Side (Ontario)
Gananoque — Pronounced GAN-an-ock-way, this is the Canadian gateway to the islands. It offers the best all-around mix of culture and adventure on the Ontario side: theater at the Thousand Islands Playhouse, helicopter tours, kayaking, and boat cruises all within easy reach.
Kingston — The largest city in the region and Canada's first capital, Kingston sits where the St. Lawrence meets Lake Ontario. It's a lively university city built from historic limestone, with a serious culinary scene, museums, and landmarks like Fort Henry.
Brockville — Further east along the river, Brockville is a handsome historic city with two distinctive draws: the Brockville Railway Tunnel — Canada's first railway tunnel, now repurposed as an underground light-and-sound experience — and some of the best freshwater scuba diving in the country among sunken river shipwrecks.
Rockport — A tiny, picturesque village almost entirely organized around its marina and waterfront. Rockport is one of the closest Canadian departure points to the densest part of the archipelago, and its boat cruises thread through some of the tightest island channels in the region.
Prescott — Near the Ogdensburg-Prescott International Bridge further east, Prescott is a quiet historic town anchored by Fort Wellington, a well-preserved British fortification from the War of 1812.
When the season turns, the Thousand Islands transforms completely. The boat cruises stop, the castles close, and the St. Lawrence freezes over — but what's left is something genuinely worth seeking out: quiet trails, affordable hotels, and a set of cold-weather activities the summer crowds never see.
Ice fishing
When the river and its bays freeze solid, the region becomes one of the premier ice fishing destinations in the Northeast. The waters around Alexandria Bay, Chaumont Bay, and Eel Bay are especially prized — this is the only area in New York State with no daily catch limit on yellow perch, and they are both plentiful and excellent eating. Anglers also set tip-ups for Northern Pike and Walleye through the ice. Local bait shops on both sides of the border stay open all winter and post current ice thickness reports.
Hiking and snowshoeing
The trails that feel crowded in July are deserted by December. The Minna Anthony Common Nature Center on Wellesley Island stays open year-round with miles of cross-country skiing and snowshoeing trails winding along the frozen shoreline. On the Canadian side, the mainland sections of Thousand Islands National Park — including Jones Creek and Landon Bay — remain accessible, with compact snow trails leading to rocky ridges and sweeping views of the frozen river.
Snowmobiling
The Thousand Islands Snowmobile Club maintains over 80 miles of groomed trails on the U.S. side, connecting Clayton, Alexandria Bay, and Cape Vincent. On the Ontario side, the 1000 Islands Parkway feeds into province-wide trail networks. For downhill skiing or snow tubing, Dry Hill Ski Area in Watertown, NY, is a short drive south.
Ice skating
Skating on an outdoor rink in a historic river town is one of winter's simple pleasures here. Springer Market Square in Kingston offers free skating in the heart of downtown, surrounded by 19th-century limestone architecture. Community rinks can also be found at Winter Park in Clayton and Rotary Park in Brockville.
Indoor escapes
When the temperature makes outdoor activities unappealing, the region has solid options inside. Wineries along the Thousand Islands-Seaway Wine Trail — including Thousand Islands Winery in Alexandria Bay and Coyote Moon in Clayton — keep their tasting rooms open through the winter. The Aquatarium in Brockville is a world-class indoor discovery center with interactive aquariums, a ropes course, and river otters. The 1000 Islands History Museum in Gananoque covers indigenous history, the Gilded Age castle era, and regional pirate lore — and is open year-round.
One more reason to visit in winter
Hotel rates. Luxury waterfront properties that command premium prices in July — including the 1000 Islands Harbor Hotel in Clayton — routinely cut their rates by 50% or more in the off-season. It's the same river view for half the price.