Undersea volcanoes have several stages of growth. Debris fro frequent eruptions throughout the stages of growth build an undersea volcano up, so that it rises above sea level. Gradually, the explosive eruptions grow less frequent and the volcano becomes dormant. Eventually, erosion breaks the volcano down into flat topped seamounts, ringed by coral reefs. These seamounts are known as guyots and are found mainly in the Pacific Ocean and in the islands of Hawaii.