Governor Island is the most popular stop in the Hundred Islands and the most developed. It has a cave system open to visitors — a short swim-through tunnel at low tide leads into a chamber where stalactites hang from the ceiling — and a concrete staircase winds up to a viewpoint over the surrounding islands. From the top you get a clear sense of the park's scale: dozens of mushroom-shaped islets stretching towards the horizon in both directions.
The beach on the sheltered side of Governor Island fills up on weekends and Philippine public holidays, when day-trippers from Manila and nearby Pangasinan towns arrive in numbers. At those times the cave can have a queue. If you want peace, use Governor Island as a brief stop and push on to quieter corners of the park.