The Cocos (Keeling) Islands are an Australian external territory in the Indian Ocean, consisting of a small archipelago located roughly halfway between Australia and Sri Lanka and near to the Indonesian island of Sumatra. The region comprises two atolls made up of 27 coral islands, only two of which are inhabited (West Island and Home Island). The population of roughly 600 people is primarily made up of Cocos Malays, who practice Sunni Islam and speak a Malay dialect as their first language. There are no rivers or lakes on each atoll. Fresh water supplies are confined to water lenses on bigger islands, which are underground rainwater accumulations above the ocean. These lenses can be accessible by shallow boreholes or wells.