Most of the mountainous islands are covered in tropical rainforest and volcanic in origin. The highest mountain is Mount Apo. It measures up to 2,954 meters (9,692 ft) above sea level and is located on the island of Mindanao.[265][266] The Galathea Depth in the Philippine Trench is the deepest point in the country and the third deepest in the world. The trench is located in the Philippine Sea.