Geography of the Philippines Bay. Laguna de Bay, east of Manila Bay, is the largest freshwater lake in the Philippines. Several rivers have been harnessed for hydroelectric power. To protect the country's biological resources, the government has taken a first step of preparing a Biodiversity Action Plan to address conservation of threatened species. The islands are volcanic in origin, being part of the Pacific Ring of Fire, and are mostly mountainous. The highest point in the country is the peak of Mount Apo in Mindanao, which is above sea level. The second highest point can be found on Luzon at Mount Pulag, a peak
Laguna de Bay The lake is a multipurpose resource. In order to reduce the flooding in Manila along the Pasig River, during heavy rains, the peak water flows of the Marikina River are diverted via the Manggahan Floodway to Laguna de Bay, which serves as a temporary reservoir. In case the water level on the lake is higher than the Marikina River, the flow on the floodway is reversed, both Marikina River and the lake drain through Pasig River to Manila Bay. The lake has been used as a navigation lane for passenger boats since the Spanish colonial era. It is also used