The Philippines are a number of islands between Asia and Australia, at the western rim of the Pacific Ocean, and belongs to Asia. The Capital City is Manila. Nearly 70 Million inhabitants speak Filipino (Tagalog), English, and Spanish.
The Philippines are part of the ring of volcanoes around the Pacific Ocean. The Pacific Plate is surrounded by convergent rims, where one plated submerges under another plate. This collision produces a sort of accumulation of volcanic rocks, which form a rim of islands along the plate rim.
So the islands of of the Philippines are of volcanic origin, and the most common caves are most likely lava tubes. However, the caves I know of are all limestone (karst) caves, formed in carbonatic sediments. The limestone was sedimented in the warm and oxygene rich sea and uplifted by the forces of the colliding plates.
The longest cave of the Philippines is Odloman Cave in Mabinay. It was explored by Dutch and Belgian speleologists. A famous karst area are the Chocolate Hills on Bohol, the tenth largest island. The dome-shaped limestone hills are a typical tropic Tower Karst. The name is a result of the grass which covers the hills. It dries up and turns brown under the sun in dry season.