The Palanan Wilderness Area is a large tract of undisturbed forest which forms a large part of the combined nature preserve of the Northern Sierra Madre National Park and Peñablanca Protected Landscape and Seascape. It contains the most extensive area of preserved rainforest in the Philippines at 359,486 hectares. The larger of 2 remaining areas of intact primeval forest in Luzon (the other being a much smaller wooded area in the Cordilleras), it is considered one of the most diverse forests in the world. Known as the Palanan Complex, Palanan Rainforest, or Palanan Wilderness Area, it was designated a wilderness area in 1979. In 1997, it was designated a national park also known as the Northern Sierra Madre National Park. In 2003 this conservation area was combined with the neighboring Penablanca Protected Landscape and Seascape