National Geographic : 1958 Jul
/ U. S . Coast Guard, Official Four Tons of Concrete Blocks Smash the Ice in Simpson Strait Seeking a safe deepwater route for supply convoys, three United States Coast Guard vessels and a Canadian icebreaker last summer charted a Northwest Passage amid desolate Arctic islands. Here, strung with life lines and armed with axes, men dangle from the prow of the U.S.C .G.S. Spar. Blocks are dropped onto the ice to smash a passage through the floes or used as anchors to warp the ship free when it becomes fast. 142 ...