There’s not a whole lot to do in Puerto Princesa, however there are some great sights outside of the city.
The Dallas Inn can arrange tours to the Underground River in Sabang and trips to Honda Bay. The cost of the Underground River tour (which includes the a/c minivan ride to Sabang, entrance to the Underground River, buffet lunch and guide) is 1,500p / person. You will need to arrange the permit yourself, which can be done in Puerto Princesa. The cost of the permit for foreigners is 400p / person.
A trip to Honda Bay will cost 1,400p / person, including lunch, ride in an a/c minivan and guide.
There’s a big market you can explore selling everything from fresh fish to souvenirs. The Immaculate Conception Cathedral and the Plaza Cuartel are really nice as well.
A tricycle ride anywhere around town costs 8p/person.