Machias Seal Island is a small, rocky island located in the Gulf of Maine, between the states of Maine and New Brunswick, Canada. It covers about 50 acres and is known for its rich marine life, particularly seabirds like the Atlantic puffin and common murre. The island is uninhabited, except for seasonal researchers and birdwatchers. The island is also notable for its disputed sovereignty, with both the United States and Canada claiming ownership. A lighthouse, built in 1832, stands on the island, serving as a navigational aid for ships in the area. Access to the island is typically limited to boat tours during the summer months.