170223-N-OH262-625 ATLANTIC OCEAN (Feb. 23, 2017) Third Assistant Engineer Sam O'Donnell pulls Engine Utility Billy Chiguina through the water during a rescue-at-sea exercise. O'Donnell and Chiguina are both surface rescue swimmers and civil service mariners assigned to the hospital ship USNS Comfort (T-AH 20). Comfort's underway period was part of the 2017 Comfort Exercise (COMFEX). The exercise is a quarterly training battery designed to keep the medical personnel, support staff and civil service mariners who serve aboard the ship proficient in their duties. Comfort provides an afloat, mobile, acute surgical medical facility when called upon to the U.S. military, and hospital services to support U.S. disaster relief and humanitarian operations worldwide. (U.S. Navy photo by Bill Mesta/Released)