St. Mary's River State Park


7 Reviews

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St. Mary's River State Park Facts

States: Maryland
Counties: St. Marys
Length: 7.5 miles
Trail end points: Camp Cosoma Rd. north of SR 5 and St. Mary's Lake
Trail surfaces: Dirt
Trail category: Greenway/Non-RT
ID: 6032205

St. Mary's River State Park Description

Nestled amongst the trees of St. Mary's River State Park, trail-goers will find an 8-mile path that loops around St. Mary's Lake, offering beautiful natural scenery and the chance to catch a glimpse of many types of birds and other wildlife. The single-track dirt trail is popular with hikers, mountain bikers and horseback riders.

Parking and Trail Access

The trail is located off State Route 5 on Camp Cosoma Road (3 miles north of Great Mills and 24 miles north of Point Lookout State Park). Trail access is provided from the parking lot at the boat ramp.

St. Mary's River State Park Reviews

Beautiful moderate trail with a "but"

I've hiked this trail with my dog a couple times, the complete 7.5 loop around the lake. The scenery is really pretty and you will get a workout going up and down rises. You'll hear birds and see squirrels, maybe deer. It really is a lovely trail, and especially in the fall when the leaves are changing.

That being said, there are a few negatives. The signage is not very good, so grab a map when you start. The first time I walked it I got quite mixed up near the end because I didn't know which trail I needed to follow. Luckily I saw other people and went the way they did.

Be alert for cyclists! The trail is quite popular with folks on bikes, and you can't always hear them coming until they are almost upon you. I had to snatch my dog out of the way a couple times.

***Use as much tick prevention as possible. Honestly, permethrin your clothes and deet yourself. This past weekend I took my dog for a hike. I sprayed both of us down with repellant before we even left the parking lot. About halfway through I realized I could literally see ticks clinging to the grass. They were all over my pants and shoes, even with the spray. As soon as we got home we both got a bath. I lucked out, but my poor dog was covered with hundreds of tiny ticks. Luckily his oral flea/tick prevention killed them as soon as they bit, but he is still pretty itchy. I probably won't go back in tick season, and may opt to leave the pup home when I do.
In all fairness, we hiked the park in April and didn't have any issues then.

Review Update

Okay, I finally realized my goal of completing two laps of this course and here's what I have learned: 1) Around miles 1.5 to 3.0 are where you will find the most mud puddles/standing water, which will be heavy with the biters and stingers. 2) the 3.0 to 4.25 section is where you can get easily disoriented. There is an unmarked pole just before the 4.0 marker, that pole has two trails. Keep going straight when you pass that pole. One last fork is after the 4.0 marker, take the path that goes to up and to the right. 3) At the 5.0 marker is a good (but not steep) downhill. 4) At the 6.0 marker, you have about under a half a mile (mostly uphill) before you come out of the canopy and hit a gravel road. 5) At the 6.75 mile marker, there will be two paths that will both take you back to the forest. The path on the right is shorter. 6) When you get back to the canopy, you will see two posts; take the FIRST post and take a sharp right; this will lead you to the final half mile on the trail. You will need insect repellent on this course; however, the drier that the trail is, the better.

Worth riding

Definitely rooty, with a bit of mud (well, a lot of mud after heavy rains) to make things interesting. Either direction is good but I like clockwise best. There is the original 7.5 mile trail that makes a good ride itself. the more recent pine trail goes off the main loop on the far side of the lake, and adds some climb and interesting sections. Its not well marked (branches off at about 4 miles (going clockwise) and re-enters at about the 5 mile marker (downed tree across the trail there). Not real crowded, even on weekends. more challenging than Cedarville and on par, but different than Rosaryville.

Not a 'walk in the park' trail, but super fun

This has been my 'home trail' for the last 2+ years. I'm a moderate/intermediate MTBr and this trail is NEVER boring. I continue to hone my skills on this trail. Tons of roots, bridges, short uphills, short down hills, short flat/fast sections and there’s always the possibility of getting muddy and fairly dirty each time you ride it (who doesn’t like to get dirty?!). This trail is a mix of a lot of cool stuff. First time riding, I’d go counter clockwise (I think it’s a bit faster/easier this way). Second time, switch it up and go clockwise (I think it’s a bit more technical going clockwise direction for some reason). Fun both ways for sure.
I’ve ridden a 26r Hard Tail the majority of my time here, but recently had the chance to ride a 29r full suspension bike. With the HT, I had to carefully choose my line (there’s some BIG roots out there) but with the 29r FS it’s SO MUCH MORE FUN! The 29r FS just rolls over anything and everything! Depending on the type of bike you have, the difficulty changes, but don’t be discouraged in coming to ride this trail, It’s worth it regardless of skill set or bike type. I would travel up to an hour or so to ride this trail, I think it’s that good. This is not a trail for the young kids 10 and under (unless they are REALLY confident and have a legit kids MTB) or you don’t mind walking a lot of sections. Head to Cedarville with the young kids and ride the Orange trail for a VERY positive MTB experience!


Well done trail run!

I am a novice to trail running, but this was a course that is good for beginners. There are some uphills and downhills and the course is fairly technical (exposed tree roots) but is is manageable if you watch your step. The trail is well marked (look for the white flashes painted on the trees), but be careful near the last half mile near the end. There is one marker with a white and yellow marker on it. If you see this, you may have gone too far. Lastly, make sure you have a strong and effective insect repellent, as the woods are very thick. The trail is shared by horseback riders, and their mounts leave plenty for the swarms of horseflies! Other than that I recommend this for trail runners looking for a moderate run and road runners looking for a change of pace.


The day after Thanksgiving Daniel, his Dad Victor, and myself did this trail and had a great time. This is a single track ride and it is not a ride in the park, so to speak. All though the main trail is 7.5 miles, there is over 11 miles of trails now. The Southern Maryland Mountain Bike Club, all though a small group, are working hard at building more trails. I would not drive a long distance out of my way to do this ride but if you are in the area you should put this on your "to-do-list". The park has some great single tracks trails. The only bad part of the ride is there are a lot of tree roots and is some what of a technical ride. I could see where after a rain or in the spring this could be a very wet ride.

St. Mary's Lake

"This trail is difficult for novice bikers but it's a good ride for experienced bikers. When the trail is wet parts of it are nearly impossible to walk or run. In the summer get out early due to the killer mosquitos. Also, check for ticks when you get home. Lyme disease is very real around these parts."

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