The ocean, especially the deep ocean, dominates this world; it is the largest single habitat on the planet, a habitat whose inhabitants constitute the most common forms of life on this planet. By its immense influence on the global climate systems, this vast realm continually shapes life on the land. It is the least understood realm on the planet, home to a system of life that we did not know existed ? nor was it one we could even have imagined - only found by accident in the late twentieth century. We are tampering blindly with this vast realm, destroying segments of the intricate and complex systems of life within it. We plunder its riches and only return our waste. We need to know the ocean; it just may control our fate. <br /><br /> Presently, there is a gap in our ability to study this realm: we can no longer only sit on the surface, peering in from time to time; we need to look beneath the ocean's obscuring surface, at any point, for extended periods. Small research submersibles and self-contained diving gear only become available in the later half of the twentieth century, allowing us to venture beneath the ocean's surface. However, these have severe limitations, in their endurance (usually measured in hours) and operational conditions. The heyday for underwater research was the late nineteen-sixties; at that time there were, around the world, over fifty fixed undersea habitats operated by half a dozen countries. Their complexity, and their large on- and off- shore support requirements, eventually lead their sponsors to abandon of most of these habitats. There are only two left operating today, both of which are just off the coast of Florida, with one converted to a dive-access hotel in a coastal lagoon and the other anchored well offshore, the last remaining active undersea research habitat in the world. <br /><br /> We need a new type of ocean-going research vessel that will operate as an observation post on the deep ocean. Scientists need to collect a variety of data, over scales ranging from millimetres to kilometres and time spans ranging from seconds to days, years, and even decades; do this through a continuous, comprehensive, long-term, manned presence on and in the ocean, down to the seafloor, instead of trying to piece together processes by taking intermittent snapshots of a relatively few places and events; and keep this whole endeavour open and accessible to the entire world. A vessel that bridges the surface that isolates the two separate but intricately linked worlds, above and below, would enable researchers to be in both places at once. What such a vessel would be like, how it would function, and what challenges it would deal with; such a vessel is the focus of this thesis.

The ocean, especially the deep ocean, dominates this world; it is the largest single habitat on the planet, a habitat whose inhabitants constitute the most common forms of life on this planet. By its immense influence on the global climate systems, this vast realm continually shapes life on the land. It is the least understood realm on the planet, home to a system of life that we did not know existed ? nor was it one we could even have imagined - only found by accident in the late twentieth century. We are tampering blindly with this vast realm, destroying segments of the intricate and complex systems of life within it. We plunder its riches and only return our waste. We need to know the ocean; it just may control our fate. <br /><br /> Presently, there is a gap in our ability to study this realm: we can no longer only sit on the surface, peering in from time to time; we need to look beneath the ocean's obscuring surface, at any point, for extended periods. Small research submersibles and self-contained diving gear only become available in the later half of the twentieth century, allowing us to venture beneath the ocean's surface. However, these have severe limitations, in their endurance (usually measured in hours) and operational conditions. The heyday for underwater research was the late nineteen-sixties; at that time there were, around the world, over fifty fixed undersea habitats operated by half a dozen countries. Their complexity, and their large on- and off- shore support requirements, eventually lead their sponsors to abandon of most of these habitats. There are only two left operating today, both of which are just off the coast of Florida, with one converted to a dive-access hotel in a coastal lagoon and the other anchored well offshore, the last remaining active undersea research habitat in the world. <br /><br /> We need a new type of ocean-going research vessel that will operate as an observation post on the deep ocean. Scientists need to collect a variety of data, over scales ranging from millimetres to kilometres and time spans ranging from seconds to days, years, and even decades; do this through a continuous, comprehensive, long-term, manned presence on and in the ocean, down to the seafloor, instead of trying to piece together processes by taking intermittent snapshots of a relatively few places and events; and keep this whole endeavour open and accessible to the entire world. A vessel that bridges the surface that isolates the two separate but intricately linked worlds, above and below, would enable researchers to be in both places at once. What such a vessel would be like, how it would function, and what challenges it would deal with; such a vessel is the focus of this thesis.