More and more lithium batteries are being used, when a cell goes thermal runaway and you put it under water this is what happens. Now think of how many lithium batteries are throw in dumpsters, trash cans, without any thought of them igniting? This is why battery fires are so hard to put out, and water alone won't work. Also, with some fire departments under funded not every department always has the foam trucks to put these fires out. Here is a video of the fire burning underwater. #fire #foam