Carlls Creek and the town of Babylon are located off Great South Bay on the mainland side of Long Island just north of the Fire Island Inlet. Babylon is 14 miles northeast of Jones Inlet and 35 miles east of New York City (by land).
The Carlls River and the Town of Babylon are reached via Great South Bay, or the State Boat Channel from the Oak Island Channel Cut.
From the east on Great South Bay, the route is mainly unmarked, but depths on the northern edge of the bay past the Robert Moses Causeway (60-foot fixed vertical clearance) remain a good seven to eight feet in depth. Once you have cleared the bridge heading east (or approaching form the west), pick up red nun 4 and green can 5 at the mouth of the Carlls River, and then head north along the unmarked channel, proceeding slowly and feeling your way along with a depth sounder.
If you are approaching from the State Boat Channel, exit into the Oak Island Channel at Grass Island, and then follow the series of nun buoys up to flashing green buoy 9, where you will turn towards red nun 4 and green can 5 about a mile west. Once clear of red nun 4 and green can 5, head north along the unmarked channel, proceeding slowly and feeling your way along with a depth sounder.
The primary marina on the river is located to starboard about a mile up form the rivers mouth. This marina accepts transient guests and has repair facilities available.