English: Ben Eoin Marina, in the community of Ben Eoin, Nova Scotia, is located on the East Bay of the Bras d'Or Lake on Cape Breton Island in the Canadian province of Nova Scotia.

East Bay is one of three long narrow arms that extend to the east of the main body of the Bras d'Or Lake, the others being St. Andrews Channel and Great Bras d'Or Channel. As East Bay is part of the Bras d'Or Lake system and the lake is essentially a fiordal system connected to the North Atlantic via two restricted channels at the Great Bras d'Or Channel north of Boularderie Island and the Little Bras d'Or Channel to south of Boularderie Island, the waters of East Bay are brackish, partially fresh/ salt water.

East Bay opens to the south-west directly onto the Bras d'Or Lake and lies between the Boisdale Hills to the north and the East Bay Hills to the south. The bay measures 8.3 kilometres (5.2 mi) wide at its mouth, between Benacadie Point to the north, and Middle Cape to the south and runs easterly 41 kilometres (25 mi) to its terminus at Portage. East Bay has 77.9 kilometres (48.4 mi) of shoreline.

The bay's shores are generally heavily wooded and consist mainly of bold and rocky shorelines interspersed with numerous barrachois (barrier) points and beaches. Glacial drumlin deposits form a group of islands along the northern shore of East Bay. The narrower eastern end of the bay is bridged by the East Bay Sandbar, running east-west 1.25 kilometres (0.78 mi).