|Adjacent bodies of water||Philippine Sea|
|Area||437 km2 (169 sq mi)|
|Highest elevation||518 ft (157.9 m)|
|Highest point||Mount Baliuko|
|Province||Surigao del Norte|
Siargao is a tear-drop shaped island in the Philippine Sea situated 196 kilometers southeast of Tacloban. It has a land area of approximately 437 square kilometres (169 sq mi). The east coast is relatively straight with one deep inlet, Port Pilar. The coastline is marked by a succession of reefs, small points and white, sandy beaches. The neighboring islands and islets have similar landforms.
The island is within the jurisdiction of the province of Surigao del Norte and is composed of the municipalities of Burgos, Dapa, Del Carmen, General Luna, San Benito, Pilar, San Isidro, Santa Monica and Socorro.
The first recorded sighting by Europeans of Siargao Island was by Spanish navigator Bernardo de la Torre on board of the carrack San Juan de Letrán in 1543 when attempting to return from Sarangani to New Spain. It was charted as Isla de las Palmas (Palm Island in Spanish).
Siargao Island contains one of the largest mangrove forest reserves in Mindanao, covering an area of 4,871 hectares in Del Carmen. Long stretches of wetlands indicate a potential for commercial seaweed propagation. The extensive mangrove forests of the western coast in the Del Carmen area are home to the Indo-Pacific Crocodylus porosus. A large specimen measuring 14 feet, 9 inches (4.5 meters) was found dead in 2016 
Siargao Island is greatly influenced by the winds and currents coming uninterrupted from the Pacific Ocean, intensified by the Mindanao current running westward through the Siargao Strait. The tide of Siargao is diurnal with tidal curves typically present, especially on the east coast of the island.
The island's Pacific-facing reefs are situated on the edge of the Philippine Trench, and the extremely deep offshore waters assure the ocean swells have undiluted power when they encounter the many coral and rock reefs. Siargao has excellent surfing conditions, particularly during the southwest "habagat" monsoon from August to November when the prevailing wind is offshore.
There are several islands located off Siargao. The islands in Del Carmen include Guyam Island, Pansukian or Naked Island (a sandbar), and Daku Island. These are typically included in island-hopping tours that are popular activities being offered to tourists visiting the island.
In the western coast in the municipalities of Del Carmen and San Benito are numerous islands, most of which are covered in mangrove forests. These islands include Caob, Pagbasayan, Poneas, Tona, Laonan, and Kawhagan. The tourist attractions of Sugba Lagoon and Pamomoan Beach is located in Kawhagan. The westernmost island of Siargao is Halian (under the jurisdiction of Del Carmen), located in between Siargao and the Dinagat Islands.
Off the southern end of the island are the three Bucas Grande island groups. Two of which, East Bucas Grande and Middle Bucas Grande, are part of the municipality of Dapa, while the largest island, Bucas Grande, is contiguous to the municipality of Socorro. Bucas Grande is known for the tourist attractions of Sohoton Cove, Tiktikan Lake, and the Jellyfish Sanctuary, among others.
In the past, the island could be reached via a direct domestic flight from Manila to Surigao City and then by a ferry to the coastal towns of Dapa or Del Carmen. Now, Cebu Pacific has flights from Cebu-Siargao, vice versa as well as a direct Manila-Siargao route (it stops briefly in Cebu and passengers then switch to a smaller aircraft). In March 2017, both Cebu Pacific and SkyJet Airlines commenced direct flights to Sayak Airport (SOS) Siargao island from Manila Airport (MNL), the first direct flights to the island from the capital. Additionally, Philippine Airlines has been offering direct flights from Clark International Airport to Sayak Airport since July 1, 2018. There are plans to extend the runway of Sayak Airport in Siargao, to cater to the demands of growing tourists who will be visiting this island paradise.
One of the well-known surfing spots in Siargao and the Philippines, with a reputation for thick, hollow tubes is "Cloud 9". This right-breaking reef wave is the site of the annual Siargao Cup, a domestic and international surfing competition sponsored by the provincial government of Surigao del Norte.
The wave was discovered by travelling surfers in the late 1980s. It was named by American photographer John Seaton Callahan after a chocolate bar of the same name and was featured in the United States-based Surfer magazine in March 1993. This surf trip to Siargao Island was named by Surfer as one of the "Ten Best Surf Trips of All Time" in 1995. Cloud 9 also has a reputation for being a relatively cheap destination for surfers with many accommodations, restaurants, and bars to choose from. There are several other quality waves on Siargao and nearby islands, but Cloud 9 has received more publicity than any other surf spot in the Philippines. While it is not the only wave in the Tuason Point and General Luna areas easily accessible via the long pier from the shoreline and without the need for a boat, it is easily the most popular, leading to overcrowding and the nickname of "Crowd 9" among surfers.
Siargao, particularly the municipality of General Luna and the Tuason Point area, is well known as "The Surfing Capital of the Philippines" with a reputation among surfers within the Philippines and the International scene.
The island of Siargao was a hideout for convicted American drug smuggler and surfing entrepreneur Mike Boyum, who arrived on the island in late December 1988 and who died on Siargao from a 44-day "spiritual cleansing fast" in April 1989.
Eddie Florano has also written a song called "Surfin' in Siargao" from the 2006 Ukulele World: Acoustic & Power Ukulele compilation album.
- In March 2018, journalist Karen Davila, anchor of late-night newscast Bandila, narrated in social media her family's "traumatic" experience on the island. Her son's whole chest bled from abrasions from hitting the rocks on the shallow waters while their surfing "trainer" "suddenly disappeared" after supposedly assisting the family. The journalist called out to the Siargao management, as well as the Mayor, that surfing instructors needed to be professionalized.
- In July 2019, singer Yeng Constantino complained about local medical facilities in a Facebook post. She criticized a Siargao hospital for allegedly not attending to her husband properly after he sustained a head injury while cliff diving in Sugba Lagoon.
The beach at Daku Island off General Luna
Cloud 9 Boardwalk in General Luna
Doot Beach (also known as "Secret Beach") in Dapa
Sugba Lagoon in Kawhagan Island, Del Carmen
Old lighthouse at Pacifico Beach in San Isidro
Magpupungko Rock Pools in Pilar
- Paredes, Francis Tom; Paredes, Sheila (2017). The Monosyllabic root -ao in Mindanao Languages. 8th Annual In-house Review of the Research Office of Agusan del Sur State College of Agriculture and Technology. Agusan del Sur State College of Agriculture and Technology.
- Brand, Donald D. The Pacific Basin: A History of its Geographical Explorations New York: The American Geographical Society (New York, 1967) p.123,131.
- Mascarinas, Erwin M. (28 October 2016). "14-foot dead crocodile found in Siargao". Sunstar.
- "2020 Siargao Travel Guide: Experience the Surfing Paradise of Mindanao | Lakwatsero". March 3, 2020.
- Supetran, Bernard. "The SPOT.ph Guide to Siargao Island". Spot.ph. Retrieved 17 April 2021.
- Adel, Rosette (6 January 2020). "Siargao's Sugba Lagoon to be closed for rehabilitation, DOT Caraga says". PhilStar Global. Retrieved 17 April 2021.
- "Exploring Siargao's hidden island paradise of Halian". Business Mirror. Retrieved 17 April 2021.
- Springer, Kate (2 December 2020). "These remote lagoons in the Philippines will change the way you feel about jellyfish". CNN travel. Retrieved 17 April 2021.
- Lopez, Alexander (12 April 2021). "Surigao's Bucas Grande Island opens for tourism". Philippine News Agency. Retrieved 17 April 2021.
- "DIRECT FLIGHT TO SIARGAO -". February 24, 2017.
- "PAL to fly Clark-Siargao starting July 1". Rappler.
- Cloud 9 Spot Check on Surfline http://www.surfline.com/templates/article_html.cfm?n=3&id=15607&p=1
- Mike and Bill Boyum http://encyclopediaofsurfing.com/entries/boyum-mike-and-bill
- "The Chili Peppers Almost Used 'The Philippines' As A Song Title In Their New Album". FHM.
- "Karen Davila reveals traumatic experience with family in Siargao". ABS-CBN News. Retrieved January 25, 2019.
- "Singer Yeng Constantino criticizes Siargao hospital; slammed for 'doctor-shaming'". au.news.yahoo.com. Retrieved November 5, 2019.