The Gulf, otherwise known as the Blue Hole, is a water sinkhole located within a portion of the Mark Twain National Forest. While the trail is not very interesting, the geologic feature is worth checking out and is the reason for stopping if you are in the area. The water level constantly changes depending on the season and the amount of rainfall. A small trail leads down close to the water; however, it is steep and slick, and there isn't much to hang on to. A couple of signs explain the history and geology of the sinkhole.