The start of this trail is found a few hundred feet north of Looking Glass Road (FSR #63) on a closed gravel road (shuttles are possible along this road).
The entrance of the trail is on the left, but it may be a little overgrown. From there, the trail is hard to miss. The singletrack starts off with a few steep climbs and gradually levels out into a gradual climb through dense forest on the edge of a slump (the sink the trail is named for).
The trail appears to come to an end in a clearing with no real markings, but the USFS maps show it continuing west on a doubletrack to reach Looking Glass Road (FSR #63) again. In the reverse, this is a fun rip to the bottom.