Lake HillierWhy the pink lake changed colour.

01. A pink lake beside the ocean

Lake Hillier lies on Middle Island, in the Recherche Archipelago off the southern coast of Western Australia. It is a relatively small lake, roughly 600 metres long, surrounded by vegetation and separated from the sea by a narrow stretch of land.

From above, the contrast can be striking: coloured water, a pale shoreline, green vegetation and the blue ocean. The lake is a real geographic feature, not a digitally recoloured landscape. But its famous appearance depends on environmental conditions, and photographs from different years cannot be treated as interchangeable.

02. Salt creates an unusual habitat

Lake Hillier is hypersaline: its water contains much more dissolved salt than ordinary seawater. Such conditions are difficult for many organisms, but they are suitable for certain microorganisms adapted to high salinity.

Some of these organisms produce coloured compounds, including carotenoid pigments. These compounds are associated with the biology of salt-loving microbes and can contribute red, orange or pink tones to saline environments. The colour is therefore connected to the living ecosystem, rather than to an artificial dye.

That does not mean every pink lake works in exactly the same way. Salinity, microbial communities, water depth and environmental conditions differ from one place to another. A useful explanation identifies the organisms and conditions at the particular lake instead of assuming one universal cause.

03. What the microbiome study revealed

A scientific study published in Environmental Microbiome in December 2022 examined Lake Hillier using microbial sequencing and culture-based methods. The researchers identified a diverse community that included bacteria, archaea, algae and viruses, along with several groups associated with pigment production.

Among the organisms identified were Dunaliella, Salinibacter, Halobacillus, Psychroflexus and Halorubrum. The study proposed that the lake's colour results from a combination of pigment-rich organisms, rather than attributing the entire phenomenon to a single species.

The researchers also made an important distinction: identifying likely pigment producers is not the same as measuring exactly how much each contributes to the visible colour. Their work provides a stronger explanation of the ecosystem, while leaving room for further investigation.

04. Why did Lake Hillier lose its pink colour?

The lake's recent history is essential to understanding the photograph. An exceptional rainfall event in 2022 added large amounts of freshwater and diluted the lake's salt concentration. Its familiar intense pink appearance faded.

In February 2025, Australian reporting described the lake as still discoloured. Environmental scientist Tilo Massenbauer explained that the rainfall had also introduced material from vegetation, affecting the water's appearance. He expected the pink to return as evaporation raised salinity again, but could not predict when.

The change is a useful reminder that a natural landmark is not a fixed image. A lake can retain its name and geographic identity while its water level, chemistry and visible colour change. The same processes that help create an unusual landscape can also alter it.

05. From a pink lake to the wider atlas

Lake Hillier is a different kind of curiosity from the Sailing Stones of Death Valley. There, rare combinations of water, ice and wind leave tracks in a dry lakebed. Here, water chemistry and microscopic life help explain a changing colour. Both show why a photograph is only one moment in a landscape's history.

For the wider geography of saltwater, coastlines and connected seas, continue to Oceans. Lake Hillier is a lake, not an ocean basin, but its shoreline makes the contrast between inland water and the surrounding sea especially visible.

Quick answers

Where is Lake Hillier?

On Middle Island in the Recherche Archipelago, off the southern coast of Western Australia.

Is the pink colour real?

Yes. Historical photographs document the natural colour. It is not necessary to digitally recolour the lake to explain the phenomenon.

Is Lake Hillier still bright pink?

Its intense colour faded after the 2022 rainfall. Official guidance revised in April 2026 says the colour remains variable and recovery cannot be predicted. Do not assume an older photograph shows today's conditions.

What caused the pink colour?

Research supports a combination of pigment-producing, salt-tolerant microorganisms. The precise contribution of each organism has not been fully established.