In this guide you can find out How to Find the Mirror and Get Out of The Cave.
Here’s what you need to do in order to escape from the cave.
Just try to follow these steps.
Jump over to the small ledge
Go to the neighboring chamber and call up Trico there. Climb onto the beast and, after you have mounted him, jump onto the neighboring ledge. There are two barrels here. Pick up each one of them and toss them towards Trico. The beast will either snap them in mid-flight, or after they drop to the ground.
Remain on the ledge where you have found the barrels and find a small tunnel here. You can cross it (it used to be blocked by one of the barrels). Follow the path and squeeze between the walls. You will walk into a large chamber. In here, you have to find the mirror shown in the above screenshot. Collect it, because you are going to need it to solve many puzzles later into the game.
Return to the chamber where Trico is. You will have to use the mirror here. To do this, find the wall fragment shown in the above screenshot. Use the mirror (hold down Circle) and aim it at the wall. Trico will fire a lightning bolts from his tail and destroy the obstacle. This will allow you to continue.
Use the mirror on the boulders in the passage by the chasm
Start your exploration of this chamber. Watch out after you reach the part with the huge chasm to the right, because it is easy to lose your balance here and fall down. After a while, you will reach rubble blocking your way. Aim your mirror at it and wait for lightning bolts to remove the obstacle.
Aim the mirror at the vertical planks
Soon, you will reach a large, partially-flooded cavern. Remain on the upper ledge, aim the mirror at the vertical planks and destroy them (remove the entire vertical section). You can now start jumping down to lower ledges on the right, or take a long jump into the water. Regardless of which you did, swim up to the hole that has been created as a result of destroying the abovementioned planks.
Shove over the crate with barrels
Find a chain, jump towards it and grab onto it to climb up. This way, you will make it over to the ledge above, where you find a crate with three barrels inside. You have to shove (Circle) the crate over to the hole, for it to drop down and smash. Go back down. Pick up one of the barrels and toss it into the lake, which will make Trico jump into the water. Do the same with the remaining two.
Find a big exit from this part of the cave. Call on Trico, climb onto his back and wait for him to jump onto a ledge above. He will take you to the small hole in the wall shown in the above screenshot. Jump towards the vertical wall and climb up to reach the hole and cross it. You will leave the cave and Trico will automatically join you.