The island has a land area of 12.83 ha (31.7 acres) with the southern part of the island rocky and elevated and the northern part covered by bigleaf maple and Western redcedar trees.

[2] The island was originally known as Brown Island, named by Charles Wilkes for fourteen members of his United States Exploring Expedition crew who shared the same surname.

It was later acquired by Victor McConnell, its first settler, who claimed squatters' rights.

[4][5] Thompson financed the purchase of the island through the sale of his valuable stamp collection and later built a home on it from native stone and driftwood.

[6] During his proprietorship of the remote island, Thompson used it to entertain friends and guests from the nearby Friday Harbor Laboratories.