Hoover-Diana is a deepwater U.S. Gulf of Mexico oil and gas development. The reservoir development plan is a hybrid drilling and completion program that includes remote subsea wells (Diana) connected by flowlines to a host deep-draft caisson vessel (DDCV) and platform type wells (Hoover) on the DDCV with surface trees connected to the seafloor by production risers. The Diana subsea wells were batch drilled with a dynamically-positioned (DP) drillship and completed with a new-build, moored semisubmersible. These subsea wells were designed as horizontal openhole gravel packs to deplete a relatively thin oil rim that lies between an aquifer and a large gas cap. The Hoover drilling and completion program marked the first time a drilling rig would set subsea wellheads and perform all the drilling and completion operations, including the riserless operations, from a caisson vessel.