Waves form by absorbing energy from the wind. The longer the “fetch,” or the expanse of sea over which the wind can blow without obstruction, the taller a wave gets. The taller it gets, the more efficiently it absorbs additional energy. Generally, its maximum height will equal half the speed of the wind. Thus a wind of 150 miles an hour can produce waves up to 75 feet tall. Other conditions, such as the chance superimposition of two or more waves, can cause waves to grow even bigger. The tallest wave on record was 112 feet, but occurred amid steady winds of only 75 miles an hour.
