The Natural History Museum, London, holds a collection of >6000 specimens of dry-preserved hard (mainly scleractinian) corals from the Chagos Archipelago in the Indian Ocean (British Indian Ocean Territory). These were collected from three expeditions in the 1970s. This archipelago of >50 islands includes the Great Chagos Bank which is the largest coral atoll in the world. The ecosystems are impacted very little by pollution or fishing and therefore represent an important resource for scientific study, including that of climate change. The collection is largely in good condition and extremely comprehensive taxonomically, covering ca. 75 genera. The NHM also holds some associated documentation from the original expeditions.