Composed of islands, islets, cays,[2] and more than 100 reefs, sometimes grouped in submerged old atolls,[3] the archipelago lies off the coasts of the Philippines, Malaysia, and southern Vietnam.

The Spratly Islands are one of the major archipelagos in the South China Sea which complicate governance and economics in this part of Southeast Asia due to their location in strategic shipping lanes.

The islands are largely uninhabited, but offer rich fishing grounds and may contain significant oil and natural gas reserves, and as such are important to the claimants in their attempts to establish international boundaries.

Additionally, Brunei has claimed an exclusive economic zone in the southeastern part of the Spratly Islands, which includes the uninhabited Louisa Reef.

These accumulations of biogenic carbonate lie upon the higher crests of major submarine ridges that are uplifted fault blocks known by geologists as horsts.

The long axes of the horsts, rotated fault blocks and half-grabens form well-defined linear trends that lie parallel to magnetic anomalies exhibited by the oceanic crust of the adjacent South China Sea.

[16][17][18] The dismemberment and subsidence of continental crust into horsts, rotated fault blocks and half-grabens that underlie the Spratly Islands and surrounding sea bottom occurred in two distinct periods.

During the Late Cretaceous and Early Oligocene, the earliest period of tectonic stretching of continental crust and formation of horsts, half-grabens, and rotated fault-blocks occurred in association with the rifting and later sea-floor spreading that created the South China Sea.

During the Late Oligocene-Early Miocene additional stretching and block faulting of continental crust occurred within the Spratly Islands and adjacent Dangerous Ground.

Starting with their formation in Late Cretaceous, fine-grained organic-rich marine sediments accumulated within the numerous submarine half-grabens that underlie sea bottom within the Dangerous Ground region.

Southeast and west of them, there also exist thick accumulations of sediments that possibly might contain economic oil and gas reserves, which lie closer to the Spratly Islands.

[3] Political instability, tourism, and the increasing industrialisation of neighbouring countries has led to serious disruption of native flora and fauna, over-exploitation of natural resources, and environmental pollution.

One region of the Spratly Archipelago, named Truong Sa, was proposed by Vietnam's Ministry of Science, Technology, and the Environment (MOSTE) as a future protected area.

[3] Military groups in the Spratly Islands have engaged in environmentally damaging activities such as shooting turtles and seabirds, raiding nests and fishing with explosives.

He explained that the reason the world has heard little about the damage inflicted by the People's Republic of China to the reefs is that the experts can't get to them and noted "I have colleagues from the Philippines, Taiwan, PRC, Vietnam and Malaysia who have worked in the Spratly area.

[56] According to Hanoi, Vietnamese maps record Bãi Cát Vàng (Golden Sandbanks, referring to both the Spratly and Paracel Islands), which lay near the coast of the central Vietnam, as early as 1838.

[57] In 1888 the Central Borneo Company were granted a lease to work guano "on Sprattly island and Amboyna Cay"[58] During the Second World War troops from French Indochina and Japan were in occupation.

[75] The line mentioned in the convention can be more accurately described as a shorthand for dividing islands between China and Vietnam in the Gulf of Tonkin, but not its maritime waters.

In the 1950s amid warming ties between the two countries, Mao Zedong decided to hand over Bạch Long Vĩ Island, which lies to the west of the dividing line and had Chinese inhabitants, to Vietnam.

[55] Western scholars have determined, however, that this incident is not based on verifiable references and is inconsistent with other Chinese inaction during the same time period given that, in 1885, the German Admiralty published a two‐sheet chart entitled Die Paracel‐Inseln (The Paracel Islands).

[failed verification] This occupation was protested by the Republic of China (ROC) government because France admitted finding Chinese fishermen there when French warships visited nine of the islands.

[99] In 1999, a Philippine navy ship (Number 57 – BRP Sierra Madre) was purposely run aground near Second Thomas Shoal to enable establishment of an outpost.

[110][111] In July 2012, the National Assembly of Vietnam passed a law demarcating Vietnamese sea borders to include the Spratly and Paracel Islands.

[121] In a series of news stories on 16 April 2015, it was revealed, through photos taken by Airbus, that China had been building an airstrip on Fiery Cross Reef, one of the southern islands.

The Vietnamese government fears that evidence of Champa's influence over the disputed area in the South China Sea would bring attention to human rights violations and killings of ethnic minorities in Vietnam such as in the 2001 and 2004 uprisings, and lead to the issue of Cham autonomy being brought into the dispute, since the Vietnamese conquered the Hindu and Muslim Cham people in a war in 1832.

Ancestors of Moro people were the owners of Spratly Islands prior to the arrival of the Spanish colonials in the 16th century, according to the Sultan of Sulu in the southern Philippines reported in a local paper.

[131] In January 2013, the Philippines initiated arbitration proceedings against China under the United Nations Convention on the Law of the Sea (UNCLOS) across a range of issues, including the latter's historic rights claims over parts or all of the Spratly Islands inside the nine-dash line.

[132] It also concluded that China's historic rights claims over the maritime areas (as opposed to land masses and territorial waters) inside the nine-dash line would have no lawful effect outside of what is entitled to under UNCLOS.

[145] The governments in support were Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, India, Ireland, Italy, Japan, the Netherlands, New Zealand, the Philippines, Poland, Portugal, Romania, Slovakia, South Korea, Spain, Sweden, the United Kingdom, and the United States; the eight in opposition were China, Montenegro, Pakistan, Russia, Sudan, Syria, Taiwan, and Vanuatu.

The extended coverage would allow soldiers stationed on the islands, fishermen, and merchant vessels within the area to use mobile services, and can also provide assistance during storms and sea rescues.