The United States Census Bureau reports Necker Island's land area as 45.193 acres (18.289 ha).

The remnant of a volcanic cone,[6] Necker Island is located about 120 kilometers (65 nmi; 75 mi) southeast of the French Frigate Shoals[7] on the northwestern end of a large, shallow ocean bank.

[9] Along the island's western shore, West Cove lies between Mo'o Point and the southern end of Northwest Cape.

[9][14] A seabird first observed at Necker Island and at the French Frigate Shoals and Nihoa in 1902 originally was thought to be new to science and was given the scientific name Procelsterna saxatalis and the popular name "Necker Island tern," but it later was identified as a subspecies of the blue-grey noddy, already known from farther south in the Pacific.

[10][11] Runoff from the heavily eroded rock surfaces of the island and the constant wave action that scours its underwater basalt structure interfere with the growth of corals; little coral life exists in the shallow areas surrounding the island,[11] and it lacks a fringing reef.

[10] Gray reef sharks and manta rays are common off the island, and Hawaiian monk seals populate its shores, some giving birth to pups there.

[18] This difference in form represents an earlier iteration of Hawaiian monumental architecture that offers a unique perspective on cultural norms prior to the abandonment of Necker.

[20] Artifacts excavated on Necker Island show a remarkable number of items that would normally be made out of wood rendered in stone.

These statues are up to 1.5 feet (0.5 m) in length and differ in style and medium to similar sculptures (usually rendered in wood) recovered elsewhere in Hawaii.

According to the legend, the Menehune settled on Necker Island after being chased off Kauai by the stronger Polynesians and subsequently built the various stone structures there.

[25][11] La Pérouse did not attempt to land on the island due to its nearly vertical sides and the violent seas breaking on its shore, but he sailed within a third of a league of it and named it after Jacques Necker, a Genevan banker and statesman who served as finance minister for Louis XVI of France.

[10][11][24] Although the expedition was lost at sea in 1788, it was able to send its logs home before its loss, bringing the island's existence to the attention of Europeans.

[11] In January 1859, United States Navy Lieutenant J. M. Brook aboard the survey schooner USS Fenimore Cooper visited Necker Island and determined its position.

[25] During the summer of 1859, Captain N. C. Brook of the Hawaiian barque Gambia passed the island during a sealing and exploration voyage, but did not report landing on it.

[25] As late as the early 1890s, the Kingdom of Hawaii's claim to Necker Island remained in dispute, and the United Kingdom was considering the island as a potential waypoint location for a submarine communications cable between Canada and Australia[27] as part of the British Empire telegraph network known informally as the All Red Line.

The Kingdom of Hawaii was overthrown in 1893 and replaced by the Provisional Government of Hawaii, and when the British corvette HMS Champion arrived at Honolulu in 1894, the provisional government's president, Sanford B. Dole, became concerned that the United Kingdom was about to establish a claim to Necker Island.

In 1902, the United States Fish Commission research ship USFC Albatross visited Necker Island, and her personnel thought they discovered the "Necker Island tern" there, as well as on Nihoa and at the French Frigate Shoals, during their visit, although the bird later was determined to be a subspecies of the blue-grey noddy, already known from farther south in the Pacific.

[29] On June 15, 2006, the United States established the Papahānaumokuākea Marine National Monument, with Necker Island within its boundaries.