It may look like the perfect selfie backdrop, but rangers in Melbourne have warned tourists against taking a dip in the stunning pink lake to achieve the perfect shot.

Melbourne's newest tourist attraction in Westgate Park has Millennials flocking for a photo after turning bright pink in recent weeks.

The man-made salt lake was built to replace the original saltmarsh that was there and so already contains large amounts of the mineral in the water.

But when levels are higher than normal, along with high temperatures, lots of sunlight and a lack of rain, algae growing in the lake produce a red pigment, the ABC explained.

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Bloom: The striking pink lake has drawn photographers from all over Melbourne. Photo / Instagram
Bloom: The striking pink lake has drawn photographers from all over Melbourne. Photo / Instagram

The pigment is called beta carotene and is produced as part of their photosynthesis process.

The lake — near the city's Westgate Bridge — started to turn pink last week and is expected to stay like that until later in autumn when it will return to being blue as the weather cools down and rainfall increases.

Though the algae is not harmful to local wildlife, people have been warned not to come into contact with the water.

Warning: People have been told not to come into contact with the water. Photo / Scott Barbour, Getty Images
Warning: People have been told not to come into contact with the water. Photo / Scott Barbour, Getty Images

The park authorities in Victoria have warned people keen to get a snap to stay away from the lake's edge.

"Algae growing in the salt crust at the bottom of the lake produces the red pigment (beta carotene) as part of its photosynthesis process and in response to the extremely high salt levels," Phil Pegler, manager conservation planning and programs at Parks Victoria, told the Herald Sun.

"In order to protect the sensitive saltmarsh vegetation around the lake, visitors are urged to obey all signage and any barriers in place.

Pink pigment: Algae in the lake colour the water, in response to high salt levels. Photo / Scott Barbour, Getty Images
Pink pigment: Algae in the lake colour the water, in response to high salt levels. Photo / Scott Barbour, Getty Images

"We recommend people avoid coming into contact with the water as it is very saline (salty) so can cause skin irritation."

The pink colour at Westgate Park can be seen elsewhere in Australia and around the world.

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In Victoria's remote northwest lakes Crosbie, Becking, Kenyon and Hardy in the Murray Sunset National Park are popular tourist attractions due to their pink colour.

Lake Hillier in Western Australia also turns pink during the summer as a result of algae.