The burial at sea of terrorist Osama bin Laden raised some eyebrows around the world, but for the U.S. Navy, it's a routine exercise.

To fulfill the final wishes of service members, the Navy commits to the sea an average of 20 deceased every month — veterans, retirees and other U.S. citizens, Cmdr. Danny Hernandez, a Navy spokesman in the Pentagon, said Monday.

U.S. vessels take the remains along with them and do the ceremony while the ships are on their scheduled deployments.

Some people request a specific ship for the burial ceremony. The Navy has burial at sea coordinators in Norfolk, Va., San Diego and Hawaii who work with the next of kin, but the designation of a ship depends on the vessel's schedule, location and ship availability.

On Monday Bin Laden's body was placed in a "weighted bag," an officer made some religious remarks and the remains were put on a flat board and tipped into the North Arabian Sea off the aircraft carrier USS Carl Vinson, Pentagon officials said at a news conference.

The usual Navy burials at sea are similar, though they include an honor guard that fires shots into the air and bugler that plays TAPS. The burials include caskets or urns with ashes released from the ship's side, as well as ashes scattered from aircraft over the seas.

Larger ships with more space have done multiple ceremonies while on tour, like the aircraft carrier USS Ronald Reagan, which did 14 burials on Memorial Day 2008 off the coast of Hawaii.

Because the ships are on duty, no family members can attend the service. But the vessel's commanding officer within 10 days sends the next of kin a letter telling the date and time of the burial, photos or video of the ceremony, a flag and a chart showing the longitude and latitude of where the burial took place, according to the Navy's funeral manual.

Eligible for such funeral service are active duty members of all service branches, retirees, veterans, their dependents, civilian marine employees of the Military Sealift Command and other U.S. citizens determined eligible for "notable service or outstanding contributions to the United States," the rule book says.