So, a friend and I have been trying out the new stuff in the snapshots the other day and we tested out the customized world spawning.

We made a world where there is a lava ocean at Y: 120. Yeah, by accident.
My friend asked me if you could ride a boat on it. So, I placed a boat and it broke.

But while it broke, I used my right mouse button to get inside it. And guess what, I was able to ride it. Sail it through the lava. But when I pressed my jump button, I could fly away.

Strange.