Cotuit Bay, the main body of water in town, is bounded by Cotuit to the west, Grand Island/Oyster Harbors to the east (part of the village of Osterville) and Dead Neck/Sampson's Island to the south, making the bay a quiet harbor and part of the so-called Three Bays system which includes North and West Bays. Sampson's Island is an Audubon bird sanctuary jointly managed by the Three Bays organization and can only be reached by boat. A permit is required for visitors. The bay is shallow and busy with boat traffic during the summer months. It is the site of the Cotuit Oyster Company. The beaches are beautiful here, and fishing is great!