Mariners Roost is a primitive, boat-access-only campground on Trinity Lake's main arm offering 7 campsites with picnic tables and vault toilets, ideal for boaters seeking a remote lakeside experience.

No potable water is available on-site, so campers must bring their own water or treat lake water, and the campground operates year-round on a first-come, first-served basis with no fees or reservations required.

The location provides excellent opportunities for fishing, swimming, motorized and non-motorized boating, and scenic views of Granite Peak.