This cavern is surprisingly simple, considering it is the penultimate one in the game. You will only have to solve a little puzzle. When you start the level, tap the rock face on the left and a passage opens in front of you. Follow it, going down the ladders. When it looks like you've come to a dead end, tap the wall on the right. Other stone walls will disappear, revealing the pillar to press. Press it and go down to the right. Touch the right wall again to make other walls disappear. Then go back to where you started the level by going up the ladders.
Proceed to the right. After going down a step, take the passage on the left below. Go down the steps and jump to the left, over the gap. Keep following the path that goes down and continue to the right. Arrived on the edge of a precipice, you will have to take a long leap to the right, to reach a settlement similar to the ones you saw in Cavern 4. Here too, you will notice a shimmering window that indicates the entrance to an exchange point. This trading post sells dynamite. It is advisable to stock it up, because you will need a lot of it in the last cave. But make sure you also keep at least two or three diamonds. When done, tap the wall on the right to be teleported to the black window below. Go down the wall you can climb on and kill any cavemen. The exit door is a short distance away on the right. You can reach it directly, if you still have time available. However, if you have run out of time or want to find two diamonds in the next bonus room, do as described below.
Proceed to the left and use a dynamite to break down the thin wall you will encounter. Touch the wall on the left to reveal a secret passage and knock down the next wall with another dynamite. You will come to where the pillar is. Press it and make a long run to the right to reach the exit door in seconds.