St. Mary's River State Park

St. Mary’s · Maryland Department of Natural Resources

A place to get outside.

Site 1 (Lake) May through September 6:00 a.m. to sunset October through April 7:00 a.m. to sunset Site 2 (Wildlands) Sunrise to sunset Please note that the gate is automated and will accept credit or debit cards only, as well as the swipe card issued by the park. Situated at the northern end of the St. Mary's River watershed, St. Mary's River State Park is separated into two areas, Sites 1 and 2. The Site 1 area holds the 250-acre St. Mary's Lake. Located along Maryland Route 5, between Leonardtown and Great Mills, at the end of Camp Cosoma Road, the area has become a popular freshwater fishing spot. This area has been improved by a modern comfort station, picnic tables, playground, boat launch ramps and a large gravel parking lot. Leashed pets are allowed in the state park. The day use service charge for Site 1 is credit-card only, $3/vehicle for Maryland residents. Out-of-state residents add $2. Charges are collected at the automated gate system at the entrance. Passholders (Maryland Passport, Golden Age and Universal Disability) may contact the park office at 301-872-5688 or by email ([email protected]) to receive an additional swipe card that allows free entry through the automated gate system located at the Lake Area of the park.

Official park information

Find your way.

Locations represent park land, not necessarily an entrance. Follow official entrance directions. Map tiles © OpenStreetMap contributors.

This map represents park land. Use the official park map and entrance directions for your journey.

Read before you roam.

THE FIELD GUIDE

Sources & verification

Park facts and notices are checked separately. Missing facility information does not mean a facility is absent. Official visitor page checked Oct 15, 2026.