Simunul is a municipality located in the province of Tawi-Tawi, within the Bangsamoro Autonomous Region in Muslim Mindanao (BARMM), Philippines. Geographically, it is part of the Sulu Archipelago—a chain of islands that stretches between Mindanao in the Philippines and Sabah in Malaysia. Simunul lies just south of the Tawi-Tawi mainland, specifically the island of Bongao, and is surrounded by the waters of the Celebes Sea. It is approximately positioned at 4°53′N latitude and 119°49′E longitude.

The main landmass of Simunul is Simunul Island itself, which is about 12 kilometers long and 5 kilometers wide. It is primarily of volcanic origin, with mostly flat coastal areas and a few hilly inland zones. The terrain includes sandy to loamy soil, and in some coastal areas, coral-based soils are found. The municipality also includes several smaller surrounding islands and islets such as Manuk Manka, Bohiboy, Bubuan, Tapian, and Dowan. These islands are notable for their rich natural resources, including mangrove forests, coral reefs, and sandy beaches, which support a vibrant marine ecosystem. The waters around Simunul are rich in biodiversity and are crucial to the local economy, with fishing, seaweed farming, and aquaculture being major livelihoods.

Simunul has a tropical climate classified as Type IV by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), characterized by relatively even rainfall throughout the year. Temperatures typically range between 27 to 32 degrees Celsius. The island is affected by both the southwest monsoon (Habagat) and northeast monsoon (Amihan), which bring varying levels of rainfall, especially from May to November. As a low-lying coastal municipality, Simunul is vulnerable to natural hazards such as coastal erosion and the impacts of rising sea levels.

The municipality is politically divided into 15 barangays, including Bakong, Buan, Duhul Batu, Kadurong, Kanibungan, Manuk Manka, Maruwa, Sibak Latih, Simunul (Poblacion), Sipangkot, Sukabulan, Tonggusong, Tubig Indangan, Tongehat, and Tulluban. Among these, Tubig Indangan holds historical significance as the location of the Sheik Karimul Makhdum Mosque, believed to be the oldest mosque in the Philippines, established in 1380 CE. The population of Simunul is predominantly Muslim, mainly from the Sama-Bajau ethnolinguistic group. Local languages include Sama and Tausug, though Filipino is also spoken.

Simunul is not directly accessible by air, as it lacks an airport. Travelers typically reach it by motorboat or pump boat from Bongao, the provincial capital of Tawi-Tawi, which is about a 30 to 60-minute sea journey depending on weather and sea conditions. Bongao is home to Sanga-Sanga Airport, the nearest air transportation hub. Given its proximity to Malaysia and its location within the Sulu Archipelago, Simunul holds strategic geopolitical importance, particularly in regional trade, migration, and maritime security. As part of the Bangsamoro region, it also plays a meaningful role in the broader context of peacebuilding and autonomy in southern Philippines.