A substantially circular watercraft has a buoyant, generally toroidal hull supporting a rigid deck with an outer periphery in substantial conformance with the perimeter of the hull. The deck has an opening located above the central opening of the hull to permit placement of power means to drive and steer the watercraft. The hull is made of a substantially rigid material and in a preferred embodiment the hull and deck are formed from a molded plastic. The leading edge of the watercraft is equipped with a Carolina flare which provides greater ease of movement through the water.

The present invention concerns a marine-based carbon sequestration buoyant structure. The structure comprises a frame, a peripheral platform area (1) for housing accommodation and amenities, and carbon sequestration apparatus, wherein the frame supports the peripheral platform area and carbon sequestration apparatus (2,3). The present invention further relates to a method of carbon sequestration, the method comprising providing the marine-based carbon sequestration buoyant structure in a major ocean gyre circulation