Deep sea crab (image from BBC news)
Things living in the deep sea live under much higher pressure than those living on the surface. This means that they usually die when they are collected and brought up to research vessels. From the BBC, I read about how an aquarium in France has constructed a box that will allow animals to be held at very high pressure, about 18 megapascals (equivalent to 1800m below the surface). The box is small and has walls 10cm thick, but will house deep-sea crabs and shrimp.
Apart from showing the public what deep-sea creatures look like, the box will also be used to conduct research on how species deal with increasing pressure. In a situation where the seas are warming, some species may have to migrate deeper in order to survive. Research into how they may survive this would help with modelling scenarios for species distributions, or other climate change-related studies.