Hidden beach in the Bacuit Archipelago
 

Small Lagoon.  On the Miniloc island you can find several stunning lagoons.  One of them is the "Small Lagoon".  Through a gap in the rocks, you can swim into the lagoon.  It's also popular for cayaking.  The view with the high walls and clear water is stunning.  If you are unlucky, you will find it a bit crowdy here.  If you want to take pictures, take a waterproof camera or casing.  It's not a bad idea to wear slippers here.

Big Lagoon.  The approach to the Big Lagoon on Miniloc island is utterly impressive.  First you will see that the water becomes shallower, then your bangka will go through the entry with almost vertical natural walls on both sides to finally end up in the lagoon itself.  Really stunning. 

Secret Lagoon.  This very small lagoon is also on Miniloc island.  You can only reach it through a small hole in the rocks.  Once you crept through it, you will find yourself surrounded by walls, making you feel like you are at the bottom of a huge well.  If you want to take pictures, then a waterproof camera or casing is a must.

Caves.  The rock formations around El Nido house a number of caves, also on the islands.  In some of them, swiftlets make edible nests that are harvested for the Chinese market where they are considered a delicacy.  The most known cave is probably "cathedral cave", that earned its name due it its form.

Other.  If you want something else then the islands, then you can go trekking in the forests of the main island where you can find caves and waterfalls.  Don't do this without guidance.

Picture 1 (left): the Small Lagoon
Picture 2 (right): the Big Lagoon