7 Mysterious Geological Formations That Still Baffle Scientists

2. LAKE HILLIER // AUSTRALIA

This small, saltwater lake on an island off Western Australia is only one-third of a mile long, but its bubblegum-pink color makes it especially striking. The lake was documented in 1802 by British explorer Matthew Flinders, who took a sample of its waters but failed to understand how it got its startling hue. Tourists can visit only by helicopter, though it is safe to swim in the waters.

Scientists today suspect the color is due to the presence of a pink alga, Dunaliella salina, and/or a pink bacterium, Salinibacter ruber. But unlike other pink lakes around the world, such as Lake Retba in Senegal, Lake Hillier’s color doesn’t fluctuate with temperature or sunlight—so the investigation goes on.

Read Mentalfloss