On our last day in Sabang, we just enjoyed the beach and the beautiful village before we had to go back to Puerto Princesa the next day. We walked towards the entrance to the national park on the east side, past the pier, the rows of fine resorts in the area and the mangrove forest onto the beach area. There, we just enjoyed the beach with only us around and from time to time, there come people passing by to do zip-lining.
Most tourists just visit the Underground River in Sabang in a day tour from Puerto Princesa. The area seems crowded during lunch time, but it gets quiet later in the day.
But I really recommend staying at least a night, because it offers a dream beach and a relaxing atmosphere. Aside from visiting the majestic underground river, which is a world heritage site by the way, you can also do an early morning (where the birds are most active) Mangrove-Tour or walk to the nearby waterfalls. For the more active people, you can go climbing the Ugong Rock Cave, hike to the Daylight Hole and take pictures of the Lion cave and the Karst mountains or simply relax on the beach! And for the more culturally inclined experience, you can visit the Batak indigenous people at the nearby Kayasan village.