National Geographic : 1964 Jun
Where Thresher sank. Com mander Keach points to the spot on a relief model of the bottom (map, page 782). Rear Adm. Edward C. Stephan, for merly the Navy's Oceanogra pher, came out of retirement to lead a study of salvage and res cue in deep water. Red yarn from the ocean's glass surface to its bed shows the two Trieste dives diagramed at right. Diagram charts the wreck and two successful dives. Light er debris, such as paper, cloth, and boot, drifted hundreds of yards. Cables anchored by rail road-engine wheels hold sonar signaling devices designed to guide Trieste. sea urchins, wormholes, starfish-spread out below us on a sandy plain. Our guide weight, a 200-pound steel ball suspended on a cable 35 feet below the hull, touches bottom gently. Relieved of this weight, Trieste is now in near-perfect equilibrium; we float gracefully, drifting with a slow southeasterly current. The guide weight drags lightly behind us; electromagnetically fastened to the ship, its cable can be cut loose instantly should the ball become snagged. "On the bottom, conditions normal," I report to the surface. Our first look at the ocean floor makes it obvious that Thresher is not going to be easy 770 to find. Instead of the smooth, gently sloping topography pictured by surface depth sound ers, the relief here can easily hide any number of submarines. Huge boulders and steep ridg es frequently obscure the picture on our sonar. We had planned to search at the relatively safe level of 35 feet. But a dense "cloud layer" of fine organic matter suspended 25 feet above the bottom forces us to cruise lower. From time to time thick patches of these clouds obscure our vision entirely. The bot tom current here is gentle, rarely exceeding one-quarter of a knot, but it shifts constantly and forces us to touch bottom occasionally to correct our navigation.