From Mother Jones Environment Section:
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Back on land, the controversy surrounding Bin Laden's last splash was just beginning. But beneath the waves, nature was taking its course, quietly and methodically turning the world's most-wanted terrorist into fish food. You could say Osama bin Laden had received the ultimate green burial, courtesy of the United States Navy.
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Beyond cost—White's full-body burial services start at $9,750—there's little stopping you from visiting Davy Jones' locker, though the EPA must be notified within 30 days of your final voyage. The agency's main concern is that once sunk, bodies stay that way. Burials must take place at least three miles offshore and in at least 600 feet of water (1,800 feet in certain areas, such as the Gulf Coast). If you use a casket, the agency recommends drilling at least six three-inch holes in it to "facilitate rapid flooding and venting of air." It also suggests adding four pounds of additional weight for every pound of body weight, which means the coffin for a 150-pound person would weigh more than 750 pounds. And to make sure coffins don't pop open when they hit the water, the EPA advises wrapping them in stainless-steel chains, gift-box style.
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Results may vary depending on a burial spot's depth, temperature, and its abundance (or lack) of sea life. Generally, the deeper and colder the water, the slower bodies decompose. A 2008 paper in Forensic Sciences described the differing conditions of remains retrieved from two airplane crashes in more than 1,500 feet of water. A victim discovered off of Sicily 34 days after death was still fully dressed; a three-month-old body found off the southern coast of Africa had been "fully skeletonized" by "highly efficient necrophageous lyssianassids" (i.e., flesh-eating shrimp-like creatures).
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Gory, but that's what it means to sleep with the fishes. Capt. White speculates that Bin Laden's body has met a similar fate. Considering that the Arabian Sea is warm (right now its average temperature is in the 80s) and teeming with sharks—well, he says, "Go figure."
http://motherjones.com/environment/2011/05/bin-laden-burial-at-sea