U.S. Navy Petty Officer 2nd Class Alan Dewitt, assigned to Mobile Diving and Salvage Unit 2, performs a training dive to familiarize himself with the MK 16 MOD 1 underwater breathing apparatus at Naval Support Activity Bahrain on March 23, 2011. The Mark 16 is a re-breathable underwater system used for bubble-free operations in water conditions with low visibility. Personnel from Mobile Diving and Salvage Unit 2 are assigned to Combined Joint Task Force 56.1, which provides maritime security operations and theater security cooperation efforts in the U.S. 5th Fleet area of responsibility.