Drilling equipment passes through the moon pool on the Maersk Developer to underwater well equipment deep below the semi-submersible rig. The rig is boring an exploratory well into Statoil’s Martin prospect, with the final well expected to reach some 31,400 feet below the surface. The moon pool is an opening in the hull of the rig that allows equipment to pass through to the sea. (Jennifer A. Dlouhy / Houston Chronicle)