St. Mary’s
St. Mary's River State Park
St. Mary’s · Maryland Department of Natural Resources
The practical details.
- Managing agency
- Maryland Department of Natural Resources
- Address
- 21250 Camp Cosoma Road Leonardtown, MD 20650
- Telephone
- 301-872-5688
- Hours
- May through September; 6:00 a.m. to sunset; October through April; 7:00 a.m. to sunset
- Entry fees
- The day use service charge for Site 1 is credit-card only, $3/vehicle for Maryland residents.
We have not yet verified accessibility details. Confirm these with the managing agency before traveling.
Check notice timestamps and official updates. Conditions can change between source checks.
About St. Mary's River State 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.
Activities & facilities
Recorded from park sources. Availability and restrictions may vary by season or visitor area.
Find your way.
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Map points represent park land, not verified visitor entrances. Follow the managing agency’s entrance directions. Tiles © OpenStreetMap contributors.
This point represents park land, and may not be a public entrance. Follow official entrance directions.
Official visitor information & directions ↗Read before you roam.
THE FIELD GUIDE
How to read park closures & visitor notices
Check the affected area, source, dates, and last verification before planning a Maryland park visit.
Read the guide THE FIELD GUIDEPests, treatments & Maryland park visits
Understand pest notices, treatment schedules, and the difference between regional guidance and a documented park impact.
Read the guide THE FIELD GUIDEPlan a Maryland park day
A practical sequence for choosing a park, checking access, reading the forecast, and finding official visitor information.
Read the guideSources & 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.
- Maryland state park directory · Oct 15, 2026
- Maryland DNR lands · Oct 15, 2026
Nearby parks.
Within 35 miles in a straight line. Travel distances and entrances vary.