The anchor line does not simply keep the boat stationary. It is the diver’s umbilical cord, the means by which he makes his way to the shipwreck and, more important, finds his way back. A diver cannot simply jump off the boat, drop through the water, and expect to land on the wreck. By the time he splashes, his boat likely will have drifted several hundred feet with the current, so that it is no longer over the wreck. Even if the boat remained directly over the wreck, a diver who jumped off and descended without using the anchor line as a guide would find himself a toy in the ocean currents
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This also took me a few dives to reconcile — the anchor chain and the decompression chains where you hang out while waiting to surface.
