Finally, on his deathbed, when I pressed my dad, he said "OK, dump my ashes in [his favorite fishing spot in the ocean]."
A good friend was also my flight instructor when I got my private pilot's license. His first paying flying gig when he got his commercial pilot's license was to fly a guy over Chesapeake Bay to drop his father's ashes in the Bay. He flew a Piper J-3 Cub, which can fly with the door open. In the summer I'd fly it that way, it gives you a nice breeze.