7 once-in-a-lifetime experiences that get you below the water

There’s something special about being underwater—time slows down and you feel weightless, so thoroughly removed from the world above. Here, we’ve rounded up seven once-in-a-lifetime experiences that take that feeling and dial it all the way up. Think: sleeping on the ocean floor, drifting between two tectonic plates, coming (safely) face-to-face with a great white shark.