The only artificial island in a 1,864-island archipelago

Countries & Cities · Published 12 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: The Thousand Islands straddle the Canada–U.S. border, featuring a landscape so dense with landforms that navigation can be treacherous. While most are natural outcroppings of the Canadian Shield, one island stands alone as a man-made creation in this vast North American archipelago.

The Thousand Islands archipelago comprises 1,864 islands stretching approximately 50 miles downstream from Kingston, Ontario, into the Saint Lawrence River. The area's geology features a southern extension of the Canadian Shield, specifically the Thousand Islands – Frontenac Arch region, connecting with the Adirondacks. To qualify as an island in this specific region, a landmass must remain above water year-round and support at least two living trees.

While the archipelago is famous for its natural beauty and historical significance—including the 1779 British Fort Haldimand and various 19th-century masonry 'castles'—it also contains unique human-engineered features. Within this territory, Longue Vue Island stands as the sole man-made landmass. This stands in contrast to the surrounding natural formations, which range from massive landmasses over 40 square miles to tiny, uninhabited rocky outcroppings.

The region's geography presents significant maritime challenges. Vessels navigating the Saint Lawrence Seaway must contend with rocks and shoals that can be less than two feet underwater in otherwise deep channels. Water clarity has shifted dramatically over time; before the mid-1990s, visibility was typically only 10 to 15 feet, but the introduction of zebra mussels improved clarity to the point where the rocky bottom can be seen in 80 feet of water in some areas.

Beyond its geology, the area is a cultural crossroads. It served as a premier summer resort for wealthy families from major U.S. and Canadian cities between 1874 and 1912. Today, it remains a hub for recreation, featuring the oldest national park east of the Rocky Mountains in Canada and numerous state parks in New York, all preserved for public use and conservation.

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