The Great South Bay at the east end is, for the most part, very shallow.  Much if it is less than a foot deep at low tide.  Boats that use the bay, especially sail boats, require a shallow draft and centerboards that are adjustable.  Getting your centerboard caught in in the bottom on a windy day can lead to capsizing, or at best provide an annoying time.  On the other hand, it's usually relatively easy to walk your boat to deeper water.

The spire shown on the map in Brookhaven Hamlet, at the intersection of Beaverdam and South Country Rds., is the Old South Haven Church; the spire in Bellport is the Methodist Church.  Squassux Landing and the Brookhaven Village Association marina (43A) is shown at the east end of Beaverdam Rd.

Directly south from Fire Place Neck (Brookhaven Hamlet), across the bay, is Old Inlet on the Fire Island barrier beach.  Just to the west of it was Mattahbank a.k.a. the Fireplace Beach Club.  Both were "private" beach clubs widely used by Brookhaven Hamlet residents.  In 1968 they became part of the Fire Island National Seashore; only Old Inlet continues with docking facilities.

Smith Point County Park is on Fire Island to the east, and is reached by crossing a draw bridge at the end of William Floyd Parkway.

Old Inlet, then known as Smith's Inlet, was open to the sea until 1837 when a ship with a cargo of mill wheels and grindstones sank during a winter storm.  It caused the inlet to silt over resulting in the maritime industries of the east end of the Great South Bay to change forever.