Docking an autonomous underwater vehicle is a critical part of many current and envisioned Navy, commercial, and scientific missions. In the Defense Advanced Research Projects Agency's (DARPA) Tactical Undersea Network Architectures (TUNA) program, docking a vehicle is a key enabler for several of the proposed concepts of operation. To support the program, a series of risk reduction tests were performed to characterize the docking process of an autonomous underwater vehicle (AUV) with a suspended dock. Two methods of docking were performed: a “soft” optical dock where the vehicle tracked and followed a suspended light emitting diode (LED) beacon and a hard physical dock where the vehicle entered a tubular structure. This docking demonstration and associated data will provide design support information for the various approaches being considered for implementing TUNA and other program solutions. At-Sea Testing was performed at San Clemente Island from 18–27 April 2016. Over the course of 3 days of testing, 42 test runs were performed with the vehicle in open water conditions. Of the 11 soft docking trials performed, there were six successful soft docks, one lasting in excess of 22 minutes. Of the 25 hard docking test runs, 6 were full docks and 5 were close-docks. Overall this test sequence showed that soft docking can be performed reliably in an at-sea environment, and that hard docking requires a hydrodynamic mass differential of 5 to 1 or greater.