The Mount Bulusan Natural Park, one of the parks in the country declared by the national government as such in order to protect its ecosystem and maintain its natural beauty, covers a complex of primary and secondary forests, mystical lakes, rivers and natural springs, and the still active Mt. Bulusan which has an elevation of 5,077 feet above sea level. The natural park in south central Sorsogon Province is a 3,673 hectare nationally protected rainforest surrounding Mt. Bulusan. Designated a National Park in 1935 and now under the protection of the DENR Protected Areas and Wildlife Bureau, it is a lush forest and wildlife sanctuary reserve that features, aside from the volcano itself, Bulusan Lake, two other mountain formations known as Sharp Peak and Hormahan, and Lake Aguingay.
Bulusan Volcano, formed about 40,000 years before the present era, soars 1,565 meters high over a base diameter of 15 km. Its cracked profile, deep ravines and caves are the result of gradual buildup of outpourings from eruptions over the ages.
Mt. Bulusan has four craters and four hot springs. Crater No. 1, 20 meters in diameter and 15 meters deep, is named Blackbird Lake after the blackbirds that have made the lake their home. Crater No. 2 is oval in shape, 60 meters by 30 meters and just as deep. Crater No. 3 is the largest and deepest, about 90 m in diameter and 20 m deep. Crater No. 4, near the northeastern rim, opened during the 1981 eruption.
A substantial area of protected forest remains around the peak and slopes, including secondary grassland, freshwater lakes and pools which are is the water source for several communities and provide irrigation for surrounding agricultural land.
The forest provides natural protection from calamities such as typhoons and flash floods. It is home to fauna like the Philippine baboon, hawks, monitor lizards, various endemic frogs, snakes and other reptiles. Some say that once there were deer but none has been sighted since the 1980s.