We had a tour of mangrove forest and the cave. There are some mannequins and paintings inside. Nothing too special, there are better things to do around Krabi.
I enjoyed the hike but I was prepared for the heat and carrying a lot of water. The mountain isn't too high, takes over 3h to come up but the sun gets tiring quickly so better leave as early as you can to avoid it, especially if you visit in hot season.