Scientists used to believe the mesopelagic layer of the ocean was full of “oceanic deserts,” huge areas of water that could sustain very little life. As we have discovered new ways of looking, we’ve found that not only is that not the case, it is so dense with sea life that it scatters sonar, effectively creating a “false bottom” that puzzled seafarers for years. Scientists traditionally measured sea life using nets, but the fish that live this far down are used to dim light and sensitive to pressure changes, making them amazing at evading nets. It is likely that 95% of the earth’s fish biomass resides there, which means these “oceanic deserts” are actually vibrant ecosystems. As scientists discover new ways of looking, we continue to rediscover and reinvent our perception of this mysterious part of the ocean.