A man is stranded on an island covered in forest. One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burns everything in its path, and without intervention the fire will burn the whole island, killing the man in the process. There are cliffs around the island, so he cannot get back on if he jumps into the ocean.
How can the man survive? (The fire, at least.) There are no buckets or any other means to douse the fire with water or sand to put it out.