Pressure and total darkness. it's why bp is having such trouble capping this gusher. sun light can't penetrate the water past 1500 feet. it's pitch black down there. also at 5,000 feet below sea level there's extreme water pressure. we're talking 2300 pounds of pressure per square inch, enough pressure to actually crush a submarine, with that pressure, naturally-occurring methane gas in the ground can also cause damage. it's believed to have caused the explosion and it's freezing at that depth. normally the water temperature is in the 70s on the surface this time of year. the water is 40 degre...