The islands range in size more than 40 square miles or 100 km2 to smaller islands occupied by a single residence, or uninhabited outcroppings of rocks that are only home to migratory waterfowl.  Large freighters frequently ply the Saint Lawrence Seaway, but the area has so many shoals and rocks that vessels sometimes hire maritime pilots to help them travel through the hazardous waterway.  Geologically, the islands are located where a branch of the Canadian Shield runs south across the river to join with the Adirondacks. Around twenty of these islands form the Thousand Islands National Park, the oldest of Canada's national parks east of the Rockies. The park hosts campgrounds, inland walking trails, annual family events, as well as a national heritage building. The Thousand Islands-Frontenac Arch region was designated a World Biosphere Reserve by UNESCO in 2002. The U.S. islands include numerous New York state parks, including Wellesley Island State Park, and Robert Moses State Park - Thousand Islands located on an island in the St. Lawrence. The Thousand Islands Bridge connects New York State and Ontario by traversing Wellesley Island at the northernmost point of Interstate 81 in Jefferson County and meets Highway 137, which leads to Highway 401. The Thousand Islands Parkway provides a scenic view of many of the islands.

Shortest Border Crossing Bridge — The picture above is the world’s shortest border crossing between the United States (on the right) and Canada (on the left). Another interesting fact is that both tiny islands are owned by same man... with dual citizenship.