Big Slackwater Access offers a concrete boat ramp (29 feet wide) and soft launch option for accessing the Potomac River above Dam #4, with a large paved parking lot (23 car spaces, 14 trailer spaces) and permanent restroom facilities.

Located at the end of Dam #4 Road in Sharpsburg, this National Park Service-managed site provides access to a scenic section of the C&O Canal towpath, though all boaters must exit the river before Dam #4, which is a river hazard.

The site is free to use during daylight hours and features a turnaround area, making it convenient for both paddlers and anglers.