1. I was watching a show last night where a group of scientists built a submersible that looks like a great white shark so they could swim with the real thing. They had a near disaster when the guy inside the thing swam too deep and too far away and lost radio contact. The sub sank to the bottom and they had to rescue him, but had trouble because they had no way to communicate with him. They were freaking out and couldn't figure out why they lost radio contact so quickly. Idiots - they're attempting to communicate via radio. Radio waves are at the infra-red end of the spectrum. Water absorbs red light to a maximum depth of about 35 feet - if you're lucky. So even if the sub is only 10 feet down, if it's 50 feet out from the boat then the radio waves have to travel diagonally through about 51 feet of water - ie they're going to lose the ability to communicate. Haven't these people ever seen the movies where a submarine has to surface to communicate with the fleet? I thought these people were scientists. Anyone who's taken basic high school science should have been able to figure that out.