The highest mountain is Mount Apo. It measures up to  above sea level and is located on the island of Mindanao. Running east of the archipelago, the Philippine Trench extendes  down at the Emden Deep. The longest river is the Cagayan River in northern Luzon, measuring about . Manila Bay, upon the shore of which the capital city of Manila lies, is connected to Laguna de Bay, the largest lake in the Philippines, by the Pasig River. The Puerto Princesa Subterranean River, which runs  underground through a karst landscape before reaching the ocean, is a UNESCO World Heritage Site.