Most of what we know of the ocean actually encompasses just its top layer. Further down, past 200 meters or so, we enter what’s sometimes known as the twilight zone. It’s dark, and the pressure is intense compared to what we experience at levels closer to the surface. Go even deeper, past 1,000 meters, and the light disappears completely. The pressure is incredible. There is life down there. We’ve never seen most of it. (Sperm whales have, though: they can dive 2,000 meters or more.)
Giant squid live in the twilight zone. Until recently, when a juvenile washed up on the shore of Japan, nobody had ever seen one alive. The midnight zone, the darkest part of the ocean, we know even less about. Creatures captured there tend to die on the journey to the surface, and it’s not even possible to keep them alive in a regular aquarium. If you want to study any of these deep sea creatures, you’ll need something like this 1,300-pound contraption, which can hold a whole five gallons of pressurized seawater.