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In the high speed world, water becomes thick, dense - an alien environment that we struggle to get through. Over time a strong swimmer can manage about 2 miles an hour. But that鈥檚 nothing compared to other mammals like the dolphin, that can reach speeds 5 times faster. But it's only in slow motion that we can see why the dolphin is so much at home here, and why we aren't. Water is 800 times thicker than air - so thick that it pulls and distorts our soft bodies as we swim, causing drag which holds us back. The water doesn't distort the dolphin's body at all, passing smoothly over it. The dolphin has much thicker skin, like rubber, that stops his blubber from flapping. So while we struggle to make headway, the dolphin is barely trying, and when they need to go faster, they can make it look effortless.