I wonder why the U.S. military buried Obama at sea?

Why didn't they cremate him to rid us of the memory that he ever existed? Or why didn't they either bury him in the ground with a large tombstone that would warn other terrorists not to mess with the U.S., or why not quarter his body and place his four limbs at the four corners of Afghanistan (that's what happened in Braveheart, but I guess we're much more civilized than that now)? Anyway, I was just wondering why they threw him out in the ocean. I guess that rids us of remembering him just as well as cremation would have.