I visited Bohol as part of a trip in the Philippines in 2011, in part for research and photography for the Ecosystem Guides book "Rainforest of South-east Asia', and in part for photography & information for work as a lecturer & guide for upcoming expedition cruises in south-east Asia.
Bohol is famous for the 'Chocolate Hills'. They are more chocolate-y at the end of the dry season...
The island of Bohol is best known for it's tiny primitive primate, the Tarsier. These would be very difficult to see in the jungle at night, as they are fast and small, and probably fairly sparse. There are a number of tourist centres where they are kept and fed, and you can great close up photographs of them. They are suprisingly aggressive little "snatch eaters" of insects, for such a cute & tiny litle teddy-bear creature. These centres are sometimes thought of a 'illegal' and immoral, and it is suggested that ecotourists visit the offical research centre, where guides can take you into a reserve and show them to you in a semi-wild situation.
The main tourist centres along the main road also have other creatures on display, such as flying fox and flying lemur.
Bohol also has one of the few places in the Philippines which is located inside the rainforest, called Nuts Huts.