Pontianak is the capital of the Indonesian province of West Kalimantan, founded first as a trading port on the island of Borneo, occupying an area of 118.21 km2 in the delta of the Kapuas River, at a point where it is joined by its major tributary, the Landak River. The city is on the equator, hence it is widely known as Kota Khatulistiwa (Equatorial City). The city center is less than 3 kilometres (2 mi) south of the equator. Pontianak is the 23rd most populous city in Indonesia (as at 2023), and the fourth most populous city on the island of Borneo (Kalimantan) after Samarinda, Balikpapan and (Malaysia's) Kuching; it is now slightly ahead of Banjarmasin.[3] It had a population of 658,685 at the 2020 Census[4] within the city limits, with significant suburbs outside those limits. The official estimate as of mid-2023 was 675,468 (comprising 337,856 males and 337,612 females).[1] The city was founded as a small Malay fishing village at the mouth of the Kapuas River. It then became the seat of the Pontianak Sultanate for several centuries. Pontianak was then incorporated into the Dutch East Indies after an agreement between the Pontianak Sultanate and the Dutch Government. During the colonial era, Pontianak was the seat of the Residentie Westerafdeeling van Borneo, one of the residencies of the Dutch East Indies.