Daredevils climb up the edge of the cliff where a cove exists and have to time their jump into the ocean at the right time. They try to jump when the water is coming out of the cave, if they don't time it right and the water takes them into the cave it can be fatal (there are memorials at the top of the cliffs). Also, the guy jumping in this video is jumping from near the bottom, the more experienced jumpers jump from near the top.