Bennett Island (Russian: Остров Бе́ннетта, romanized: Ostrov Bennetta; Yakut: Беннетт Aрыыта, romanized: Bennett Arııta) is the largest of the De Long Islands in the northern part of the East Siberian Sea in North Asia. The area of this island is approximately 150 square kilometres (58 square miles) and it has a tombolo at its eastern end. The highest point of the island is 426 metres (1,398 feet) high Mount De Long, the highest point of the archipelago. Bennett Island is part of the Yakutia administrative division of Russia.

Bennett Island was discovered by the wider world by US explorer George W. De Long in 1881, and named after the American publisher James Gordon Bennett Jr., who had financed the expedition. De Long set out in 1879 aboard the USS Jeannette, hoping to reach Wrangel Island and to discover open seas in the Arctic Ocean near the North Pole. When the ship entered an ice pack near Herald Island in September 1879 it became trapped. The vessel was crushed by the ice and sank in June 1881. At that point the party was forced to trek over the ice on foot, discovering Bennett Island during July 1881, and claiming it for the United States. They remained on the island for several days before setting out again for the New Siberian Islands and the mainland of Siberia.

In August 1901, Russian polar ship Zarya sailed on an expedition searching for the legendary Sannikov Land but was soon blocked by floating pack ice. During 1902 the attempts to reach Sannikov Land continued while Zarya was trapped in fast ice. Russian explorer Baron Eduard Toll and three companions vanished forever in November 1902 while travelling away from Bennett Island towards the south on loose ice floes.

In 1916, the Russian ambassador in London issued an official notice to the effect that the Imperial government considered Bennett, along with other Arctic islands, integral parts of the Russian Empire. This territorial claim was later maintained by the Soviet Union.

Some individuals assert American ownership of Bennett Island, and others of the De Long group, based on the 1881 landing. However, the United States government has never claimed Bennett Island, and recognizes it as Russian territory.

Bennett Island consists of Early Paleozoic, late Cretaceous, Pliocene, and Quaternary sedimentary and igneous rocks. The oldest rocks outcropping on Bennett island are moderately tilted marine Cambrian to Ordovician sedimentary rocks. They consist of an approximately 500-metre (1,600 ft) thick sequence of argillites with minor amounts of siltstone, and limestone that contain Middle Cambrian trilobites and 1,000 to 1,200 metres (3,300 to 3,900 ft) of Ordovician argillites, siltstones, and quartz sandstones that contain graptolites. These Paleozoic rocks are overlain by Late Cretacecous coal-bearing argillites and quartzite-like sandstones and basaltic lava and tuff with lenses of tuffaceous argillite. The Late Cretaceous strata is overlain by basaltic lavas ranging in age from Pliocene to Quaternary. The Quaternary volcanic rocks form volcanic cones.

Little has been published about the climatology of Bennett Island in the English language literature. Dr. Glazovskiy stated that the annual precipitation on Bennett Island varied from 100 mm (3.9 in) at sea level to 400 mm (16 in) at the crest of the Tollya Ice Cap.

Bennett Island has the largest permanent ice cover within the De Long Islands. In 1987, the permanent ice cap of this island consisted of four separate glaciers that had a total area of 65.87 square kilometres (25.43 sq mi). All of these glaciers were perched on high, basaltic plateaus bounded by steep scarp-like slopes.