A sandy, low-lying island formed on a base of aeolianite limestone, Rottnest is an A-class reserve, the highest level of protection afforded to public land.

Following establishment of the Swan River Colony (now Perth) in 1829, the island was initially used by British settlers for agricultural purposes, and a permanent settlement was built in Thomson Bay.

It is administered by the state's Rottnest Island Authority, which on 1 July 2017 became part of the newly created Department of Biodiversity, Conservation and Attractions.

[11][12] The island is a popular recreational and tourist destination, with daily ferry services from Perth, the state's capital and largest city.

[14] The land that is now Rottnest Island was inhabited by Noongar people until rising sea levels separated it from the mainland of Western Australia about 7,000 years ago.

[19] The island was observed and explored by various Dutch, French and English maritime expeditions from around 1619 onward, including by Frederick de Houtman around 28 July 1619.

[22][23] Waeckende Boey (under command of Samuel Volkersen[a]) had been searching for survivors of Vergulde Draeck, which had been wrecked off the western coast of Australia in April 1656.

This large island to which we have been unwilling to give a name, leaving this matter to the Honourable Lord Governor-General's pleasure, may be seen at 7 or 8 miles' distance out at sea in fine weather.

In his 1681 chart, English captain John Daniel marked an island as Maiden's Isle, possibly referring to Rottnest.

[29] Other explorers who stopped at the island included members of the French expedition of Nicholas Baudin in Naturaliste[30]: 83, 138–150  and Geographe in 1801 (when he planted a flag and left a bottle with a letter)[31] and 1803, Phillip Parker King in 1822, and Captain James Stirling in 1827.

Aboriginal people who refused assignment were sent to Rottnest Island to be "civilised", and were used in chain gangs to perform hard labour including farming, quarrying and collecting salt.

[38] Most of the island's historic Settlement—including Government House (Hotel Rottnest), the church, Salt Store, museum, gift shop, original waterfront cottages and The Quod—was built by forced Aboriginal prison labour working under extremely harsh conditions.

[39] Six Aboriginal prisoners were sent to Rottnest Island in August 1838 under the superintendence of Constable Laurence Welch and a small military force:[40] Helia, for murder; Buoyeen, for assault; Molly Dobbin, Tyoocan, Goodap and Cogat, for theft.

A quadrangular building was constructed in 1863–1864 and generally referred to as "the Quod"; it was used for tourist accommodation until 2018, when it was closed after decades of protests by Aboriginal people.

Len Collard describes these artefacts, such as glass and ceramic spearheads, as an important demonstration of transitional cultural engineering through use of traditional methods to modify the new materials of European settlement.

[60] The reformatory buildings were adjacent to the Quod and included a workshop, a kitchen, two large dormitories, a school room and four small cells.

A light railway was built from the jetty at Kingstown Barracks on Thomson Bay, to transport materiel and munitions to the guns.

The 9.2-inch battery, however, was saved from disposal because the high cost of removing and shipping the guns to the mainland exceeded their value as scrap metal.

[78] A staffed lookout at Bathurst Point included a signalling station which relayed shipping information between Wadjemup Lighthouse at the centre of the island and Arthur Head at Fremantle.

Section 3, subsection 4 of the Parks and Reserves Act 1895–1955 provided legislative scope for the Rottnest Island Board of Control became a Body Corporate on 24 July 1956.

Reptiles include dugite (Pseudonaja affinis), the southern blind snake (Ramphotyphlops australis), King's skink (Egernia kingii), bobtail (Tiliqua rugosa), marbled gecko (Christinus marmoratus), west coast ctenotus (Ctenotus fallens) and Burton's legless lizard (Lialis burtonis).

[93] Domestic cats were introduced to Rottnest both as pets and as predators of commensal pest animals such as the black rat and house mouse at various times since European settlement.

[96] The Rottnest Island daisy (Trachymene coerulea) is a commonly occurring flowering native which is also grown widely as an ornamental garden plant.

A Pinus radiata plantation was established by internees during World War I, roughly bordering the main settlement, The Basin and Bathurst.

Nearly 200 years of farmland clearing, firewood collection and bushfires has denuded much of the 19 square kilometres (7.3 sq mi) of large trees, and a fragile and fresh water-scarce environment has limited natural recovery.

[106] It was held that, as the island authority had promoted the site as a venue for swimming and had not put up a warning notice, it was liable for causing the injury.

[107] A snorkel trail at Parker Point features underwater interpretative plaques that give information about the marine environments surrounding Rottnest.

For many years during the twentieth century, the water supply was rainwater harvested from several large bitumen-sealed catchment areas behind Longreach Bay.

In 2004, a new 600 kW (800 hp) wind-diesel system was erected; other works at the time included upgrades to the power station and the installation of low load diesel generators.

Tasks vary, including guided tours, tree planting, litter collection, and the building of access boardwalks and stairs.