This was one of the highlights of our trip! While it is a rather expensive activity, it is a unique experience that we enjoyed tremendously. To describe it in short, it is a lake on an island, in the lake there is a volcano (active, by the way, you can see smoke coming from the ground in several areas), in the volcano there is another lake. The view is breath-taking, photographer's heaven. The hike to the summit is great, not particulary difficult (even if a bit dusty). A few more notes, just so you can have the full picture of the experience and fully enjoy yourself. I would suggest to not take the horse ride to the top, they are not taking good care of the animals, they look pitiful. If enough people refuse to take the horse, maybe they will improve their condition. Our guide was not great, just waked in front of us and that's about it. This suited us just fine, since we wanted to explore by ourselves, but you should have this in mind. We booked a full-day tour from Manila, that included transportation to and from, boat and guide. This gave us peace of mind, and we didn't have to worry about making separte arrangements for each section of the trip. Oh, and make sure you have a waterproof bag for the boat trip and a change of clothes, you will need it.