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The Thousand Islands

An archipelago of granite islets where the St Lawrence leaves Lake Ontario, straddling the border, dotted with cottages and one full castle.

Updated 19 October 2026

The Thousand Islands

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Typeisland
WhereOntario
Nearest cityGananoque
Best seasonJune to October
Time to allowTwo to three days
Getting thereAlong the St Lawrence between Kingston and Brockville, about three hours from Toronto
EntryFree; boat cruises and castle entry charged

Where the St Lawrence drains Lake Ontario, the river is scattered with well over a thousand granite islands, some large enough for villages and some holding a single tree and a single house, and the border between Canada and the United States threads between them. Boat cruises from Gananoque and Kingston are the standard way to see it, weaving through channels past cottages built by wealthy families a century ago. The most extravagant of these, Boldt Castle, sits on the American side, abandoned unfinished in 1904 when the owner's wife died and left decaying for decades before restoration. On the Canadian side a national park protects a scatter of islands for camping and paddling, and a skydeck tower gives the aerial view.

History

The Iroquois Confederacy and Ojibwa people lived in or visited the islands, which they called Manitouana, the garden of the Great Spirit. In the half century from 1874 to 1912 the archipelago was a fashionable summer resort, chiefly for wealthy New Yorkers, with grand hotels, steamboat tours and summer houses, among them masonry castles such as Castle Rest of 1888, Singer Castle on Dark Island and Boldt Castle on Heart Island, left unfinished for over 75 years after George Boldt's wife died; the islands were also a centre of boating, and local yacht clubs hosted the Gold Cup power boat races for nine years running (Wikipedia, Thousand Islands).

Highlights

  • A boat cruise - threading the channels between island cottages.
  • Boldt Castle - the abandoned and restored castle on the American side.
  • Kayaking the channels - paddling between the smaller granite islets.
  • The skydeck - the tower view over the archipelago and the border.

When to go

June to October is the season, with cruises running and the water warm enough to swim in late summer; autumn colour through the islands in early October is excellent. Everything closes for the winter freeze. Boldt Castle is on the American side, so passports are needed for cruises that land there.

What to expect

Cruises that stop at Boldt Castle cross into the United States, which means carrying a passport and clearing customs, and Canadian-only cruises skip the castle entirely, so read the itinerary before booking. The river is busy with pleasure boats in high summer. The dressing on your salad is named after this place, which is roughly the level of local myth-making.

Nearby

Kingston's fort and old town are half an hour west; Ottawa is two hours north.

Key facts

Location44.3333° N, 76.0000° W · map

Source: Wikidata, item Q1050549, read on 18 October 2026.

What to pack for The Thousand Islands

Chosen from what this place is for. Tap a kit for the full checklist.

  • Reef-safe sunscreen - High SPF that will not bleach the coral you are swimming over. Find on Amazon
  • Quick-dry clothing - Board shorts or synthetics that shrug off spray and dry fast. Find on Amazon
  • Shelter suited to the place - Tent, tarp or hut booking - match it to the terrain and rules. Find on Amazon
  • Quick-dry towel - A microfibre towel packs small and dries in minutes. Find on Amazon

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Opening times, ticket prices and seasonal closures change - check the official source before you go: official site.

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