https://phys.org/news/2018-07-lava-flies-roof-hawaii-boat.html

The U.S. Geological Survey says explosions of varying sizes happen whenever 2,000-degree (1,093-degree Celsius) lava enters much colder seawater. Some of those explosions can be so tiny they are hard to see. But when the conditions are just right, much larger explosions send molten rock and other debris high into the air, according to USGS geologist Janet Babb.

The lava punctured the boat's roof, leaving a gaping hole, firefighters said.