Press Release

HOUSTON, Dec 15, 2004 (BUSINESS WIRE) -- Diamond Offshore Drilling Inc. (NYSE:DO) reported that the semisubmersible drilling rig Ocean Vanguard parted two of its eight moorings during hurricane force winds and high seas in the Norwegian sector of the North Sea last night. No personnel were injured, the rig is stable and the well had been shut-in and secured in anticipation of the storm.

Shore-based personnel are being mobilized to the unit to assist with evaluation and any necessary repairs. The Ocean Vanguard was operating in approximately 1,200 ft. of water in the Norwegian sector of the North Sea at the time of the event.

Diamond Offshore is a leader in deep water drilling. The Company's fleet of 45 offshore drilling rigs consists of 30 semisubmersibles, 14 jack-ups and one drillship. The fleet is located in the waters of six of the world's seven continents.

SOURCE: Diamond Offshore Drilling Inc.

Diamond Offshore Drilling Inc., Houston Les Van Dyke, 281-492-5370