U.S. Coast Guard Petty Officer 2nd Class Conor Dahl monitors the operation of a decompression chamber during a simulated dive emergency Jan. 6, 2020, and U.S. Army Sgt. 1st Class William D'Angelo observes the exercise aboard the Coast Guard Cutter Polar Star (WAGB-10) approximately 10 miles north of McMurdo Station, Antarctica. Dahl is a Coast Guard diver, and the decompression chamber allows the crew to perform lifesaving procedures in the event of a dive emergency. The crew of the Polar Star, a 399-foot heavy icebreaker, is working to break a channel in the ice surrounding McMurdo Station in order to bring in refuel and resupply vessels as part of Operation Deep Freeze — the U.S. military’s contribution to the National Science Foundation-managed, civilian U.S. Antarctic Program. U.S. Coast Guard photograph by Senior Chief Petty Officer NyxoLyno Cangemi