Indonesia is known as an archipelagic nation, with thousands of islands stretching from Sabang to Merauke. Yet when it comes to the exact number of islands, the government has reported several different figures.
The numbers range from 17,508, based on a military mapping exercise in 1987, to 13,466, following a government survey conducted between 2007 and 2010. The Geospatial Information Agency (BIG) recorded 17,374 islands in 2023.
The gap between the highest and lowest figures reaches 4,042 islands. This difference is not simply the result of counting errors. Each figure comes from a different period, mapping method, and set of criteria.
For nearly four decades, mapping and verification efforts have continued to update Indonesia’s list of islands, including their names and coordinates.
From 17,508 to 13,466 Islands
The figure of 17,508 islands, which is often cited, came from Indonesia’s military mapping agency in 1987. It was later included in the explanatory notes to Law No. 6 of 1996 on Indonesian Waters, which stated that Indonesia had approximately 17,508 islands.
A similar figure appeared in government documents decades later. In August 2017, the Cabinet Secretariat reported that Indonesia had 17,504 islands within its sovereign territory.
The four-island difference shows that even official government documents have not always used the same figure.
A much larger change followed a three-year survey conducted by BIG beginning in 2007. The survey recorded 13,466 islands across Indonesia.
This figure was subsequently submitted to the United Nations in 2012, during the 10th United Nations Conference on the Standardization of Geographical Names (UNCSGN).
Why did the number fall by more than 4,000? One explanation lies in the criteria used to identify an island. Earlier surveys reportedly had not fully excluded sandbanks and reefs that only emerge when the sea level is low.
Article 121 of the United Nations Convention on the Law of the Sea (UNCLOS) defines an island as a naturally formed area of land, surrounded by water, that remains above water at high tide.
Land that becomes submerged at high tide does not meet that definition. Under these criteria, not every patch of land visible at low tide can be counted as an island.
Why Does the Number Keep Growing?
After the figure of 13,466 was submitted in 2012, the government’s work continued. Subsequent efforts also focused on verifying islands and standardising their names to ensure that each had a clearly defined geographical identity.
At the 30th session of the United Nations Group of Experts on Geographical Names (UNGEGN) and the 11th UNCSGN, held in New York from 7 to 18 August 2017, Indonesia reported 16,056 named islands. This was an increase of 2,590 from the list submitted in 2012.
However, the process was far from complete. Arif Havas Oegroseno, then Deputy for Maritime Sovereignty at the Coordinating Ministry for Maritime Affairs, said that another 1,448 islands still needed to be validated and verified. The figure was reported by the Cabinet Secretariat.
Data collection and updates continued in the following years. According to BIG's historical records, Indonesia had 16,771 islands in 2020. The figure rose to 17,024 in 2022 and reached 17,374 in 2023.
Yet, figures for the same year have not always been consistent. In a December 2023 column published by Kompas, BIG Head Muh Aris Marfai reported 17,061 islands as of 2023, up from 17,024 the previous year.
This figure only included islands that had been surveyed, mapped, assigned coordinates, named, and standardised. Aris also noted that the actual number could be higher.
On 12 December 2024, Aris reported that the Gazetteer of the Republic of Indonesia, the country's official register of geographical names, listed 17,380 islands. He also mentioned that around 63 islands had been added over the preceding few years.
Counting Islands Is More Than a Numbers Game
These varying figures show that documenting an island is not a task that can be completed in a single survey. The government must establish whether each landform meets the definition of an island, determine its coordinates, and standardise its name.
Under Presidential Regulation No. 116 of 2016, BIG is responsible for standardising geographical names across Indonesia. Submitting island names to the United Nations also helps strengthen the validity of Indonesia's geographical data.
However, registering an island does not automatically establish international recognition of sovereignty over that territory.
Arif Havas Oegroseno made this clear in August 2017, as quoted by Kontan. The United Nations does not recognise a country's sovereignty over an island simply because its name has been registered.
At the same time, then-BIG Head Hasanuddin Z. Abidin warned that islands in border areas where territorial agreements with Indonesia had yet to be reached could raise sovereignty concerns.
The varying figures, therefore, are more than statistical discrepancies. They reflect a lengthy process of identifying, mapping, and establishing the geographical identity of Indonesia's many islands.
