Thousand Islands

Geography and Geology

The Thousand Islands archipelago is situated at the head of the Saint Lawrence River, beginning just east of Kingston, Ontario. The international border bisects the river channel, placing islands in either Ontario, Canada, or New York State, United States. The islands themselves are the visible peaks of an ancient granite ridge known as the Frontenac Arch, a southern extension of the Canadian Shield that connects to the Adirondack Mountains in New York. This unique geological formation creates a rugged terrain of rocky islands and deep, clear channels. The ecological significance of this transition zone between two major geological provinces led to its designation as a UNESCO World Biosphere Reserve in 2002. The definition of an island in this region is specific, requiring land to remain above water year-round and support at least two living trees.

The underwater topography is as dramatic as the surface views, with sudden drop-offs and hidden shoals. A vessel less than 25 feet from shore can be in over 200 feet of water, while rocks and shoals less than two feet underwater can be found in the centre of otherwise deep waters. This makes navigation outside marked channels hazardous, particularly at night. Water clarity has improved markedly since the mid-1990s due to the filtering effect of invasive zebra mussels. Visibility, once only 10 to 15 feet, now allows a rocky bottom to be observed in 80 feet of water in some areas. This clarity has also made the river a destination for freshwater shipwreck diving, with wrecks like the America, Islander, and Keystorm resting at various depths suitable for different skill levels.

History and Development

Prior to European contact, the islands were known as Manitouana, or the Garden of the Great Spirit, to members of the Iroquois Confederacy and Ojibwa people. The region became a strategic waterway during the War of 1812, with fortifications like Fort Wellington in Prescott and sites on Chimney Island bearing witness to the conflict. Museums about the war exist on both sides of the river. The area's modern identity was forged in the late 19th and early 20th centuries when it became a summer resort for wealthy families from New York City, Chicago, Cleveland, Pittsburgh, and Canadian cities.

This period saw the construction of grand hotels and the use of steamboats for extensive tours. Wealthy summer residents built vacation homes, creating a historically important collection of architecture from that era. Several masonry castles were constructed, including the first, Castle Rest, built in 1888 and later destroyed. The most famous extant examples are Singer Castle on Dark Island and Boldt Castle on Heart Island. George Boldt's castle was left unfinished for over 75 years after his wife's death in 1904 but has been under renovation by the Thousand Islands Bridge Authority since 1977. The region was also a centre for recreational boating, with large steam yachts designed by Nathanael Herreshoff and three local yacht clubs hosting the American Power Boat Association's Gold Cup Races for nine consecutive years.

Thousand Islands National Park

Established in 1904 as the St. Lawrence Islands National Park, Thousand Islands National Park is the oldest national park east of the Canadian Rockies. It is one of Canada's smallest national parks, covering about 24.4 square kilometres. The park comprises 21 islands, two mainland properties, and a visitor centre at Mallorytown Landing. Much of the park is only accessible by boat, encouraging exploration by kayak, canoe, or powerboat. Activities include camping on island sites, hiking inland trails, and participating in annual family events and interpretive programs.

Park operations are seasonal, typically running from mid-May to mid-October. Reservations for campsites and oTENTik shelters open in early February for the upcoming season. For the 2026 visitor season, reservations opened on February 2. Regular admission and camping fees apply, though Parks Canada occasionally offers periods of free admission, such as one concluding on September 7, 2026, which was also the last day for discounted camping and overnight stays. The park provides opportunities for stargazing, wildlife viewing, and using the Parks Canada red chairs placed at scenic lookouts. Visitors can use the Parks Canada app for self-guided tours and must be aware of regulations regarding wildlife, water safety, and camping.

Recreation and Attractions

Boating is a central activity in the Thousand Islands. The sheltered channels and countless bays are used for cruising, sailing, and fishing. Marinas, boat rentals, and tour cruises are available from communities on both sides of the border. Notable natural attractions include the Lake of the Isles, a secluded area behind Wellesley Island accessible through narrow passages like the International Rift. Potter's Beach on Grindstone Island, conserved by the Thousand Islands Land Trust, is one of the region's few beaches with a fine, shallow sandy bottom. Eel Bay, southwest of Wellesley Island, is known for fishing, especially for pike.

The Thousand Islands Land Trust conserves over 8,500 acres of land with many creeks, nature preserves, and over 30 miles of trails open year-round. The Trust runs annual programs like TILTreks, TeenTreks, and KidsTreks that include field trips and presentations on wildlife. Historic attractions draw significant interest. Boldt Castle on Heart Island is accessible by boat or tour from Alexandria Bay, New York. Singer Castle on Dark Island is privately renovated and open for tours that highlight its secret passageways and hidden wine cellars from the prohibition era. Maritime museums include the Antique Boat Museum in Clayton, New York, which houses George Boldt's luxury houseboat La Duchesse, and the Thousand Islands Boat Museum in Gananoque, Ontario, with a collection of 36 boats.

Communities and Transportation

The largest city in the region is Kingston, Ontario, a metropolitan centre of more than 170,000 people marking the western gateway. Brockville, Ontario, is another significant Canadian population centre to the east. On the American side, the largest city is Watertown, New York, with a population of about 25,000 located twenty miles inland from the river. Seasonal communities like Thousand Island Park in New York grow significantly in the summer. Villages such as Alexandria Bay, Clayton, and Gananoque serve as bases for tourists with accommodations, dining, and shopping.

The primary transportation link across the border is the Thousand Islands Bridge, which connects New York State and Ontario by traversing Wellesley Island. It meets Highway 137, which leads to Highway 401. The waterfront is served by New York State Routes 12 and 37 and by the Thousand Islands Parkway in Ontario. The Parkway also has the Waterfront Trail for cyclists. Passenger air service is available at Watertown International Airport in New York, with daily American Airlines service through Philadelphia, and at Norman Rogers Airport in Kingston, Ontario, with service on FlyGTA Airlines and Pascan Aviation. Smaller regional airports include Maxson Airfield near Alexandria Bay and Brockville-Thousand Islands Regional Tackaberry Airport northwest of Brockville.

Conservation and Stewardship

Conservation efforts in the Thousand Islands involve government agencies, land trusts, and community groups. The UNESCO Biosphere Reserve designation highlights the ecological importance of the Frontenac Arch region. Thousand Islands National Park protects representative ecosystems and species. The Thousand Islands Land Trust is a major non-profit organization that acquires and manages conservation lands with public access and runs educational programs for all ages.

Collaborative models are used to manage shared resources. The Thousand Islands Parkway Trail Advisory Committee is a community-led partnership that advises on the maintenance and safety of the multi-use recreational trail along the parkway. A pilot project partners with the Elizabethtown Snowmobile Club to groom the trail in winter for use by snowmobilers, pedestrians, and cross-country skiers. This model was informed by the success of the Ottawa Valley Rail Trail. The partnership requires snowmobilers to hold an Ontario Federation of Snowmobile Clubs permit and follow its rules, with the club providing trail marking, maintenance, and wardening services to improve safety for all users.

Cultural Notes and Thousand Island Dressing

The region's name is attached to Thousand Island dressing, a popular condiment. According to The Oxford Companion of Food and Drink, the name presumably comes from the archipelago. Several origin stories exist within the region. One common version describes how a fishing guide's wife, Sophia LaLonde, made the condiment for shore dinners. The story claims actress May Irwin requested the recipe and gave it to George Boldt, who instructed the Waldorf-Astoria's maître d'hôtel, Oscar Tschirky, to put it on the menu in 1894. Sociologists note that multiple conflicting stories exist among the islands and villages, with no strong written evidence to support any single claim.

The region's cultural calendar includes events that reflect its community life. These include a fall scarecrow contest in Clayton with public voting, fishing tournaments like the Points Tournament Series at Long Point State Park, and the 1000 Islands Punkin Chunkin event. Museums like the PumpHouse in Kingston offer bilingual exhibitions on topics like bee health. Performance venues host concerts, such as those by the Orchestra of Northern New York, and family theatre performances. The region is also promoted as a destination for weddings, honeymoons, and business conferences, with venues ranging from waterfront resorts to national brand hotels.

Notable Islands and Features

The largest island in the group is Wolfe Island, which is entirely in Ontario. Other large islands include Grindstone Island and Wellesley Island in New York, and Howe Island in Ontario. Adjacent to Wolfe Island but part of New York is Carleton Island, the site of the ruined Fort Haldimand built by the British in 1779. Deer Island, north of Alexandria Bay, is owned by the Skull and Bones secret society. A pair of islands called Zavikon Island are often incorrectly said to straddle the border with a short international bridge. They are entirely in Canada.

Ironsides Island is an uninhabited rocky island near Alexandria Bay owned by The Nature Conservancy. It is home to one of the largest great blue heron rookeries in northern New York, with over one thousand herons returning to breed each April, and was listed as a National Natural Landmark in 1967. Calumet Island near Clayton formerly featured a castle mansion belonging to tobacco tycoon Charles G. Emery. Longue Vue Island is noted as the only artificial island in the region. Just Room Enough Island is recognized as the smallest inhabited island in the world.

Questions about Thousand Islands

Where is Thousand Islands National Park and what can I do there?

Thousand Islands National Park is located on the Canadian side of the St. Lawrence River between Kingston and Brockville, Ontario. Established in 1904, it includes 21 islands, two mainland properties, and a visitor centre at Mallorytown Landing. Visitors can camp on islands, hike trails, paddle by kayak or canoe, and join interpretive programs. The park is largely accessible by boat, and reservations for campsites open in early February for the May to October season. For 2026, reservations opened on February 2 for visits between May 15 and October 12.

Can you visit Boldt Castle and how do you get there?

Yes, Boldt Castle on Heart Island is a major tourist attraction. It is located on the American side of the river near Alexandria Bay, New York. The castle is accessible only by boat. Visitors can take a public tour boat from Alexandria Bay or from Canadian ports like Gananoque, or arrive by private vessel. The castle, under ongoing restoration by the Thousand Islands Bridge Authority since 1977, is open seasonally for tours. The 120-room mansion was originally built by hotel magnate George Boldt between 1900 and 1904.

What is the best way to explore the Thousand Islands?

Exploring by water is highly recommended. Boating allows access to secluded bays, island parks, and historic castles. Visitors can bring their own boat, rent one locally, or take guided sightseeing cruises from towns like Kingston, Gananoque, Brockville, Alexandria Bay, or Clayton. For land-based exploration, the scenic Thousand Islands Parkway in Ontario offers a 37 km multi-use recreational trail for driving, cycling, and hiking with river views. The trail is maintained year-round and, in winter, is groomed for snowmobiling, walking, and skiing under a partnership with the Elizabethtown Snowmobile Club.

Is the Thousand Islands region good for fishing?

Yes, the Thousand Islands region is recognised for freshwater fishing. The St. Lawrence River and its bays are habitats for species like northern pike, muskellunge, smallmouth and largemouth bass, and walleye. Popular fishing spots include Eel Bay near Wellesley Island, known especially for pike. The area hosts several fishing tournaments, including a two-day bass points tournament at Long Point State Park in Three Mile Bay, with events typically running from 7:30 AM to 3:30 PM on tournament days.

What is the connection between the Thousand Islands and the salad dressing?

Thousand Island dressing is named after the region. While its exact origin is disputed and multiple stories exist, one popular account claims it was created in the islands by Sophia LaLonde, wife of a fishing guide. The recipe was supposedly given to actress May Irwin and then to hotelier George Boldt, who introduced it at the Waldorf-Astoria Hotel in New York City in 1894. Sociologists studying the stories found they vary between different islands and villages, with no single claim having definitive written evidence, making the dressing's origin a subject of local folklore.

Sources: Wikipedia and current public reporting, checked by the Your Space Hamilton desk. Last updated 2026-10-20.