Coral reefs are usually not found outside of the Tropic of Cancer and the Tropic of Capricorn. This is because a. water cools as it moves away from the equator. The coral reefs require warm temperatures for their development and survival. The zone between the Tropic of Cancer and the Tropic of Capricorn is the torrid zone. It is the warmest zone of the Earth as it receives the maximum amount of sunlight.