There is also a communication cable that connects to special helmets, which are also equipped with lights and video cameras. Cold is another factor. The water temperature is in the 40s. But for all the advanced training and high-tech gear, the deep ocean still poses special risks. The temperature is lower.
Visibility is affected.
So your senses that you've become accustomed to on the surface aren't nearly as helpful. Diving amid airplane wreckage carries the threat of a diver cutting his suit or umbilical on jagged strips of metal. And divers must work quickly, because it takes a long time to return to the surface. Even so, the divers will still have to decompress for about two hours in a decompression chamber on the Grapple. The Navy is outfitting the Grapple with a second decompression chamber, the diver said.