The Spar is a deep-draft floating steel caisson, which can be designed to drill, produce and store oil. It is very stable and relatively insensitive to deck loads. Drilling and production equipment are supported on the decks above the waterline. Oil may be stored in the lower portion of the hull. The centerwell protects drilling and production risers down to 650 feet. The Spar can be moored with conventional or taut catenary mooring lines using embedment or pile anchors. Because of its deep draft and large displacement mooring line dynamic loads are relatively low. Fabrication and installation plans together with cost estimates are included for a 36-well design for Chevron in the Gulf of Mexico. Predicted motions under normal and maximum sea states are shown together with the results of global motion analysis using both frequency and time domain programs. The sensitivity of the design to mooring parameters, draft, diameter and Spar mass properties is discussed. Potential applications are briefly reviewed.