Corals in oceans can thrive as deep as 650 feet (250 meters). Corals are mostly found in shallow areas at a depth less than 60 - 150 feet. Shallow corals get most of their energy from sunlight that filters deep into the water.
Contrary to the popular notion that corals are seen in warm and shallow water, it has been discovered that many corals also survive in dark water.
Corals in ocean grow best in warm water at about 70 – 80 degrees Fahrenheit (21 – 29oC). Deep corals, below the sunlit zone, get their energy from organic materials and zooplankton.