CASCO, Maine — Two men tried to traverse Thompson Lake in Casco using a vehicle equipped to handle both water and land Sunday. But the six-wheel all-terrain vehicle found a terrain it was ill-suited for: a partially frozen lake.

Robert Boisvert, 52, of Oxford and Robert Bagley, 57, of Raymond were described by the Maine Warden Service as “cold but unharmed” after the men were rescued by an airboat just before 3 p.m. Sunday.

Cpl. John MacDonald said the wheels on the small, boatlike all-terrain vehicle serve as paddles in the water, but the vehicle, once floating, couldn’t advance through the crust of ice on the lake and couldn’t reach the lake bottom to drive. As a result, it was left spinning its wheels, suspended in a hole in the ice, he said.

MacDonald said Boisvert, the driver, and Bagley, the passenger, then attempted to climb out of the vehicle onto the ice to pull it toward the shore, but fell into the water.

Game Wardens Neal Wykes and Peter Herring rescued Boisvert and Bagley and were able to tow the six-wheeler to within 20 yards of shore, where ice prevented further movement.

MacDonald said the wardens had to leave the vehicle floating on the lake until the ice melts and it can be pulled to land.