Taal Volcano is a complex volcano located on the island of Luzon in the Philippines. It is the second most active volcano in the Philippines with 33 historical eruptions. All of these eruptions are concentrated on Volcano Island, an island near the middle of Taal Lake. The lake partially fills Taal Caldera, which was formed by prehistoric eruptions between 140,000 to 5,380 BP. Viewed from Tagaytay Ridge, Taal Volcano and Lake presents one of the most picturesque and attractive views in the Philippines. It is located about 50 km (31 mi) south of the capital of the country, the city of Manila.
The volcano had several violent eruptions in the past causing loss of life in the island and the populated areas surrounding the lake, with the death toll estimated at around 5,000 to 6,000. Because of its proximity to populated areas and its eruptive history, the volcano was designated a Decade Volcano, worthy of close study to prevent future natural disasters. All volcanoes of the Philippines are part of the Pacific Ring of Fire.
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite, or in an artificial explosion caused by humans. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not made. Crater lakes covering active (fumarolic) volcanic vents are sometimes known as volcanic lakes, and the water within them is often acidic, saturated with volcanic gases, and cloudy with a strong greenish color. For example the crater lake of Kawah Ijen in Indonesia has a pH of under 0.5. Lakes located in dormant or extinct volcanoes tend to have fresh water, and the water clarity in such lakes can be exceptional due to the lack of inflowing streams and sediment.