Senior Research Technician Roman Marin III helped lower the ESP and DWSM into the MBARI test tank, where the system was checked for leaks and its buoyancy adjusted. The entire system weighs several thousand pounds in air, but only about 100 pounds underwater, because of buoyancy provided by air in the pressure housing (as well as the white, rectangular blocks of foam bolted to the top of the frame). Because the system is so light in seawater, MBARI's remotely operated vehicles can pick up and move the ESP from one spot to another with ease. The extra buoyancy also allows the deep ESP to float back up to the sea surface after a heavy 