The Bay of Fundy (Baie de Fundy) is a bay on the Atlantic coast of North America, on the northeast end of the Gulf of Maine between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine. The Bay of Fundy is known for its high tidal range and the bay is contested as having the highest vertical tidal range in the world with Ungava Bay in northern Quebec and The Severn Estuary in the UK. The name "Fundy" is thought to date back to the 16th century when the Portuguese referred to the bay as "Rio Fundo" or "deep river".

The bay was also named Baie François by explorer/cartographer Samuel de Champlain during a 1604 expedition led by Pierre Dugua, Sieur de Monts which resulted in a failed settlement attempt on St. Croix Island.

Portions of the Bay of Fundy, Shepody Bay and Minas Basin, form one of six Canadian sites in the Western Hemisphere Shorebird Reserve Network, and is classified as a Hemespheric site. It is owned by the provinces of New Brunswick and Nova Scotia, and the Canadian Wildlife Service, and is managed in conjunction with Ducks Unlimited Canada snd the Nature Conservancy of Canada.