Hillier is about 600 metres (2,000 ft) in length by about 250 metres (820 ft) in width.[2] The lake is surrounded by a rim of sand and a dense woodland of paperbark and eucalyptus trees[3] with a narrow strip of sand dunes covered by vegetation separating its northern edge from the northern coast of Middle Island. The most notable feature of the lake is its pink colour. The vibrant colour is permanent, and does not alter when the water is taken in a container. The source of the pink colour is considered to be due to the presence of the organism Dunaliella salina.[4] Air is the best mode of transportation for viewing the lake.