U.S. Navy Chief Warrant Officer 3 John Sullivan, assigned to Mobile Diving and Salvage Unit (MDSU) 2 Company 2-4, tests a MK 20 underwater breathing apparatus prior to going into the water to repair a screw propeller on coastal patrol warship USS Firebolt (PC-10) during the ship's husbandry dive in Mina Salman, Bahrain, March 7, 2011. MDSU-2 is deployed with Commander, Task Group 56.1 supporting maritime security operations and theater security cooperation efforts in the U.S. 5th Fleet area of responsibility.