Two Coast Guard divers give the “OK” signal after entering McMurdo Sound, Antarctica, Feb. 6, 2016. Divers deployed aboard the Coast Guard Cutter Polar Star for Operation Deep Freeze 2016 inspected an old ice pier posing a potential hazard to a supply vessel at the National Science Foundation’s McMurdo Station. (U.S. Coast Guard photo by Petty Officer 2nd Class Grant DeVuyst)