When crossing an ocean in a boat, the boat sinks into the void.

What I expected to happen was...:
I expected to travel across the water in my boat like normal.

What actually happened was...:
I was going across the ocean and then my boat started to sink. Eventually my boat was about 3 blocks underwater. Later it kept sinking and eventually it was all black and i was in the void at a block height of -65.
When I restarted the game my boat disappeared and I was at the top of the ocean again.

Steps to Reproduce:
1. Place a boat in the water
2. Just go forward for a while
3. Eventually the boat will sink into the void