Pulau Sapi, literally known as "Cow Island" in Malay is just off the south-western tip of Pulau Gaya. The 25-acre (10 ha) island features one of the nicest beaches in the park and most popular with tourists for snorkeling and scuba diving. Between 10am and 4pm the island gets quite busy with foreign tourists but after the last ferry leaves it becomes a tranquil island with only those staying overnight.It is developed with tourist facilities that includes a jetty, picnic shelters, barbecue pits, tables, changing rooms and toilets. The forest is inhabited by macaques. Camping and campfires are allowed with the permission from the Park Warden.
The Tunku Abdul Rahman Marine Park comprises a group of 5 islands located between 3 to 8 km off Kota Kinabalu. The park is spread over 4,929 hectares, two thirds of which cover the sea. Before the Ice Age, it formed part of the Crocker Range mass of sandstone and sedimentary rock on the mainland. However, about one million years ago, the melting ice brought about changes in the sea level and parts of the mainland were cut off by the sea to form the islands of Gaya Island, Sapi Island, Manukan Island, Mamutik Island and Sulug Island. Evidence of this can be seen from the exposed sandstone of the coastline forming the cliffs, caves, honeycombs and deep crevices.