Minecraft wiki entry for Boat, associated text: When a boat moves over a bubble column, it begins to shake. If the bubbles are caused by a magma block, all passengers are expelled and the boat sinks. In Java Edition, a sunken boat cannot be re-floated; it must be replaced. In Bedrock Edition, a boat resumes floating when it emerges from the currents keeping it down, or when the bubble column is blocked or removed.