Mount Guiting-Guiting is the highest mountain in the province of Romblon located at the heart of Sibuyan Island and dominates the entire island. Guiting-Guiting, in the local Romblomanon dialect, means "jagged". The mountain is one of the focal points of Sibuyan's declaration as a biodiversity haven. The entire island has been compared numerous times with the biodiversity endemism rate of the Galapagos islands. This endemism prompted much of the mountain and its slopes to be protected under the Mt. Guiting-Guiting Natural Park, established in 1996. The park also encompasses nearby Mt. Nailog (789 masl) to the west.
It is often referred to as Mount G2, although the nickname is not accepted by the locals as it disrespects the indigenous name of the sacred site. The mountain is open all year round for hiking. Two trails currently exist: the Tampayan Trail from the north, and the Olango Trail from the south. Hiking permits and guides are secured from the DENR office in Magdiwang town. The entire upper trails consist of exposed, broken, and sharp ultramafic rocks and boulders. The summit area of Mt. Guiting-Guiting is primarily a heath land and grassland with exposed rocks on the serrated ridges of the peak.
Though the length and duration of the climb is relatively shorter, two days to climb up and one day to descend, this mountain is still acknowledged as the most difficult and technically challenging Philippine mountain to climb, alongside Mount Halcon in Mindoro and Mount Mantalingajan in Palawan.
In May 1982, under the leadership of Arturo Valdez, a joint team from the Bacolod-based Philippine Mountaineering Society (PMS) and the University of the Philippines (UP), the team assaulted the mountain, the attempt of which was to be the first in history.
It was during this expedition that one of the peaks, now known as "Mayo's Peak" was named after one of the team members, Mayo Monteza, who celebrated his birthday during the climb, while one of the water spring sources now known as "Bulod's Spring" was named after one of the local guides, Bulod, who volunteered (along with another locals) to join the climb.
The team failed to take the summit on this first attempt, but came back two weeks afterwards. On 17 June 1982, four climbers became the first to stand at the summit. Their names are Mon Ruiz, Kim Valino, Roel Tan Torres (of UP mountaineers) and Edwin Gatia of the PMS team.
Sibuyan Island has extremely high endemism largely due to its remoteness. More than half of the Island is covered with forest. Preliminary reports include that the forest density in Sibuyan is 1,551 trees per hectare making it the densest forest ever recorded in the Philippines. There exists a full range of forest gradient in the Philippines consisting of mangrove, lowland, montane, mossy forests, heathland, and grassland—from the shoreline up to the summit of Mt. Guiting-Guiting,
There are approximately 700 vascular plant species, including 54 species that are endemic to the island. These include Nepenthes sibuyanensis; Nepenthes argentii; Heterospathe sibuyanensis Becc. (Bil-is), Agamyla sibuyanensis (Sibuyan lipstick plant); Myrmephytum beccarii Elmer (Sibuyan ant plant); Begonia gitingensis Elmer (Guiting-guiting begonia).
A total of 130 species of birds have been recorded in the park, of which 102 are either known or presumed to be breeding residents. There are also nine (9) native non-flying terrestrial mammal species, nine fruit bats species, of which one is endemic, and nine (9) lizards and geckos.