Mortimer Gulch boat ramp is a cement ramp located approximately half a mile from Mortimer Gulch Campground on Gibson Reservoir in the Helena-Lewis and Clark National Forest.

A high-clearance or 4WD vehicle is highly recommended for accessing the ramp, as the approach road is unpaved and remote.

The ramp serves as the primary water access point for the reservoir and is situated in a lightly-used area about 26 miles from Augusta via Forest Road 108.