Clark's Island is the name of a small island located in Plymouth Bay in the U.S. state of Massachusetts. It was named for the first mate of the Mayflower, the ship that brought the Pilgrims to New England. The first mate was John Clarke, so the island should actually be spelled Clarke's Island. The island was initially considered for the location of the Pilgrim's settlement, but was rejected in favor of a site to the south, which became known as Plymouth, Massachusetts.