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. Siargao is known as the surfing capital of the Philippines, and was voted the Best Island in Asia in the 2021 Conde Nast Travelers Readers awards.

The island is within the jurisdiction of the province of Surigao del Norte in the mainland Mindanao and is composed of 9 municipalities of Burgos, Dapa, Del Carmen, General Luna, San Benito, Pilar, San Isidro, Santa Monica and Socorro.

Siargao is a famous tourist destination, well known for its many surfing spots and featured in the film Siargao for such qualities. Surfing is so ingrained in the identity of Siargao, that in 2022, two political families from Surigao Del Norte traded barbs over the cancellation of a national surfing competition hosted on the island.

The name originates from Bisayan siargaw or saliargaw (Premna odorata), a mangrove species that grows on the islands.

According to records from Song dynasty China and archeological discoveries from the Surigao Treasures, uncovering Hindu and Buddhist artifacts, Siargao was an island sitting astride rich maritime trading routes. The KPC (Kalaga Putuan Crescent) Visayan trade-alliance or Rajamandala, which was an Entrepôt of: spices from Ternate, silk from China, Sandalwood incense from East Timor, Gold from Caraga, Shipping from Indochina, and Camphor from Brunei, peaked in the 1000s, and was led by the Rajahnate of Butuan just to the immediate southwest of Siargao island, but was soon eclipsed by fellow Visayan kingdoms.

Afterwards, 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 (Mexico). It was charted as Isla de las Palmas (Palm Island in Spanish).

Spanish authorities, when they incorporated Siargao, placed the island under the administration of Caraga region, they reinforced the place's defenses with Mexican soldiers and settlers who became heads of households from Mexico, in 1635 there were 45 Mexican soldier-colonists, at 1670 about 81 Mexicans soldier-colonists, and in 1672 another 81 Mexicans of the same profession. By the end of the 18th century, the area was home to 3,497 native families supported by a company of Mexican soldiers garrisoning the local forts.

In the 1818 census Surigao province alone, and it's subdivision Siargao had 2,475 native families as well as 25 Spanish families from Spain to supplement the earlier Mexican immigrants and if including the province of Butuan, also a province of Caraga, there were in total 6,178 native families and 35 Spanish-Filipino families, not counting the numerous Mexican-Filipinos who assimilated into the local population and were counted as natives.