actually this isn't the entrace of the cave, halfway on the cave trek there's a part where there's a big hole on the ceiling... it's really cool especially around 12 noon when the sun shines direcly through the hole, the beam of light is just so awesome. Try to check some of these pics in google.
https://www.google.com.ph/search?hl=fil&q=agta+cave&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&biw=1271&bih=704&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=nXAmUL26PIadmQXH8IDQCg
Awesome contrasts