There are various activities available at the provincial government owned Gota and Hunungan Beach resorts (http://www.gotavillage.com), if these do not interest you, or staying here is prohibitively expensive then you should still be able to visit to avail of their services/activities. You could also go out for night fishing tour with the local fishermens if you like fishing, But remember nights are usually cold so dont forget to bring extra clothings on the tour.
Be aware that the ongoing ability of tourists visiting these islands, beaches and sensitive areas relies upon them taking care not to damage the fragile environment, annoy the people, or act inappropriately. Respect your surroundings and ensure its ongoing sustainability by taking only photographs and leaving only footprints.
Caramoan Kayaks
Rents out hobie kayaks as well as tents and sleeping bags in case you like to camp overnight on some islands