Plum Island Sound is located about eight miles west of Cape Ann on the Atlantic Ocean behind Plum Island near Castle Neck. There are not many marine facilities or marinas up Plum Island Sound, but they do exist. There are two marinas on Great Neck near the entrance, and farther up Plum Island Sound at Newbury Old Town, there are three marinas and space for anchorage.
Use NOAA Chart 13274.
From Ipswich Bay, pick up flashing red bell buoy "2" at the mouth of Plum Island Sound, just east of Castle Neck, and then set a course for red nun "8" farther in. Keep in mind that the channel does not travel a straight line from mark to mark, especially at the entrance. Having a current chart is a must, and calling ahead for local knowledge on the inlet is recommended. Once inside, use your chart and follow all aids to navigation carefully. Plum Island Sound is fairly kind and easy to navigate, but don't let it catch you off guard.