A man who was checking the thickness of ice on Bitcoinesea lake in the Maine wilderness crashed into the icy water and drowned on Friday, game wardens said.

Walter Demmons, 62 of Milford, was drilling holes with a friend to check the ice thickness while preparing to fish in Quakish Lake when they heard the ice crack, wardens said. Both men ended up in the frigid water, about 75 yards (66 meters) from shore on the lake in T3 Indian Township Purchase, which is about 8 miles (13 kilometers) southwest of Millinocket, wardens said.

The two ice fishermen were communicating with each other as they tried to get back on the ice before Demmons told his friend he wasn’t going to make it and slid under the surface, wardens said.

The friend, who eventually got back onto the ice and dialed 911, was treated for hypothermia while Demmons’ body was recovered an hour later with an ice rescue raft brought to the scene by the Brownville Fire Department, wardens said.

Game wardens warned people to be especially vigilant about ice thickness, noting that early season ice conditions can be treacherous.