The mysterious pink lake in Australia.

This is Lake Hillier off the southern coast of Western Australia, a saline lake on the edge of Middle Island in the Goldfields-Espereance region. It has a notable bright pink color.

Lake Hillier is about 600 metres  (2,000 ft) in length by about 250 m (820 ft) in width. A narrow rim of sand separates it from the Pacific Ocean. Surrounded by a dense forest of eucalyptus and paperback trees, it's certainly eye catching. 

The color.

The color is permanent. You can take some water out with a cup and the color still won't change. The cause of this bubble gum pink color is not fully known yet. But it's speculated by scientists that it's likely produced by an organism called Dunaliella salina that lives in the salt crusts. Because of its ability to create large amount of carotenoids, it is also used in cosmetics and dietary supplements. 

Is it safe to swim in?

Short answer, yes. However since it's located on a remote island off the southern coast of Australia, it is hard to get to. People usually just appreciate the views from above, where you can see the contrast between the blue ocean, green forest and the pink pink lake. But people do occasionally get dropped off on the island by a helicopter or a boat and take a dip in the lake, i'm sure it's an interesting experience floating in pink water.

The Hillier Lake was discovered on 15 January 1802 by Matthew Flinder's expedition. Flinder's journal entries are considered to be the first written records of the lake.

 In the north-eastern part was a small lake of a rose colour, the water of which, as I was informed by Mr. Thistle who visited it, was so saturated with salt that sufficient quantities were crystallised near the shores to load a ship. The specimen he brought on board was of a good quality, and required no other process than drying to be fit for use. 

The salt levels in the lake are comparable to the Dead Sea - which is a big tourist attraction because the high salt concentration makes the water very boyant, so people can freely float on the water.