Increased drilling activities in deep water since 1985, especially in the Gulf of Mexico (GOM), have revealed numerous hazards in the shallow sediments below the seabed, such as fault scarps, gas vents, unstable slopes, and reefs and shallow subsurface geologic hazards such as faults, gas-charged sediments, buried channels, abnormally pressured sands, and gas hydrates. Drilling risks associated with shallow aquifer-pressured sands or shallow water flow (SWF) sands and gas hydrates have received the most attention. These are global problems. In the GOM alone, more than US$250 million has been lost due to SWF. While the industry has matured in handling these problems, it is estimated that the losses associated with SWF sands continue to be nearly $1.7 million per well in the GOM alone.