Muskeget Island is part of the terminal moraine marking the maximum extent of the last glacial ice sheet to reach the northeastern coast.

With this large seal population, the waters surrounding Muskeget are an important feeding area for great white sharks.

[1] This vole feeds on beach grass stalks, leaves and seeds, and insect adults and larvae.

Their predators include domestic cats (which were extirpated from the island some time in the late 1800s), short-eared owls, and northern harriers.

Specialized boats designed to navigate the difficult waters around the Island depart from Nantucket Harbor.