I am sitting in a tiny submarine at the bottom of the Gulf of Mexico peering out at a menagerie of deep-sea creatures. Aboard the research ship 650m above me are a dozen students on a deep-sea biology course run by an American colleague. Having collected specimens for their projects and my own research, this all-too-brief visit to the abyss is over. The sub bathes in a blizzard of bioluminescence as it ascends through a living soup of plankton. Immersed in the relentless flashes and squirts of light created by these life-forms, I can almost grasp that the oceans contain a billion times more organisms than there are stars in the visible universe.
Another week, another ship. With just enough time to collect some cold-weather clothing, I have swapped the Gulf of Mexico for the Southern Ocean and joined an expedition to the Antarctic. Our destination is Pine Island Bay, one of the more remote nooks of the continent's coastline, where we hope to send a robot submarine called Autosub beneath a floating ice shelf for the first time.
I am walking on the crunchy, glittering frozen skin of the eastern Amundsen Sea. Some 2m of sea ice separates me from water 3,000m deep. Our away team, which is led by Mark Brandon of the Open University, is deploying a high-tech buoy on an ice floe to record its movements over the next few weeks. Mark is also drilling holes through the ice on which we are standing to find out how thick it is. The white landscape stretches to the horizon in every direction, which makes it hard to believe we are actually at sea. After an hour enjoying this seal's-eye view, we return to the ship and slither on through the ice.
We dare not go any farther into Pine Island Bay. Although there is a tempting narrow corridor of open water ahead, it is hemmed by thick sea ice on one side and a maze of icebergs on the other. If the wind were to change, the ship could easily become trapped. The waters beneath the ice shelf will have to wait for a future expedition as we switch to a contingency plan of working farther offshore.
Referees' comments on a recently submitted research proposal are trickling in by email, even out here. The proposal aims to study the 5,000m-deep Mid-Cayman Rise, which should host the world's deepest and hottest undersea volcanic springs - and possibly some of its most bizarre life. The comments are good and I cannot help daydreaming about it during my four-hour shifts watching the ship's sonar map the ocean floor.
We have mapped an area of sea floor that is three times the size of Cambridgeshire at the entrance to Pine Island Bay. Its scars tell the story of how the ice flowed out here during the last ice age - a coup for the research project led by Julian Dowdeswell of the Scott Polar Research Institute. However, despite our efforts, and those of countless others over the years, more than 98 per cent of the world's ocean floor remains unexplored. A task for several lifetimes, I hope, even if meted out in short-term contracts.
Jon Copley is a teaching fellow, University of Southampton, and science coordinator, the Natural Environment Research Council Autosub under Ice programme.