The body was jettisoned at sea so there'd be no "martyr's grave"
That's the back story. One of three things happened, though, probably.
1. The body was actually buried.
2. The body was cremated.
3. The body is preserved at some government bunker.
But I don't believe they just willy nilly dumped the body at sea for it to wash up somewhere.
The body is weighted down so that it won't float back to the surface. And, dropping it in several thousand foot deep water would assure that it didn't wash up.