Abstract: A pressure compensated dynamic seal assembly (26) for a deep submergence actuator (10). A pressure compensated isolation fluid (28) is supplied to an isolation region (34) established between a pair of opposed dynamic seals (36, 38) about a linear actuator ram (14). The isolation region is maintained at a pressure higher than an exterior fluid pressure surrounding the actuator so that any leakage past the first dynamic seal (36) will be in a direction out of the actuator, thereby avoiding any ingress of exterior fluid into the actuator. Leakage past the lower dynamic seal (38) can be tolerated because the isolation fluid is compatible with components of the drive mechanism (20) disposed within the interior (24) of the actuator. A load-bearing bushing (40) may be located between the first and lower seals.