Connecticut River Museum in Essex.
If you go to Mystic, go all the way up river and
anchor off the museum, then
dinghy ashore. Also take your
dinghy south to the Mystic draw bridge (tie up at town park on eastern shore just below the bridge) and walk around downtown Mystic.
Stonington is another great Harbor to visit.
Watch Hill also. It's a long entry through a narrow channel in Little Narragansett Bay.
Anchor behind Napatree point and dinghy ashore to town or the Napatree beach.
Gardeners Bay has great
day sailing - and is surrounded by great harbors: 3 Mile Harbor, Greenport, Sag Harbor, Dehring Harbor, Coecles Harbor. Skip Montauk Harbor its overrun by sport
fishing and people who smoke.