Been trying out the new buffet world type added in this snapshot (love it, btw) and I've been doing hardcore mode in ocean worlds. I died in one of my worlds, oh well. So I deleted it and started a new one. Clicked create new world, set up a new hardcore ocean buffet, typed in a new random seed (I think it was Please Work This Time), and I spawned in the world I had just deleted, with the island I made still completely intact, my chests still completely full, the items I died with still on the ground, even the skeleton that shot me still alive. I investigated a bit and found that the sunken ships in the ocean had all their wood and chests unlooted (but they were all in the same places) and my maps remained the same but no longer displayed my location on them; I still could fill the map by moving around, though. I ain't complaining my stuff's back but I'm pretty sure this wasn't supposed to happen.