You place 300000000 teakettles where the river passes and activate them. You'll probably cause a blackout in the whole country but who cares? Then you can cross the river. The teakettles turn into lava, produce a mushroom cloud and cause more disasters. I never said it was safe. If you don't have 300000000 teakettles for some reason then forget the idea. If you DO have 300000000 teakettles tell me what you do with your life.