11 - Tri-Coloured: Kelimutu Volcano

Kelimutu Volcano is located in central Flores island in Indonesia. This volcano is famous for its three volcanic crater lakes that are all different colours.

Each lake has it's own name and change colours throughout the year. The westernmost of the lakes is called Tiwu Ata Mbupu (Lake of Old People), and is blue. The middle lake is called Tiwu Nuwu Muri Koo Fai (Lake of Young Men and Maidens), and is green. Finally, the easternmost lake is called Tiwu Ata Polo (Bewitched or Enchanted Lake) and is red.

There is local folklore associated with the volcano that explains why each crater lake is a different colour. It was thought that the lakes were a resting place for departed souls, and Mae, a god of the afterlife, would send people to different lakes depending on what they had done in their lifetime. The Lake of Old People was where those who died of old age went. The Lake of Young Men and Maidens was where those who died at a young age went. Finally, the Bewitched Lake was where those who were caught doing bad things were placed when they died.

Each lake contains different major elements, making them all different colours. The colour of the lakes change independently of each other as a result of chemical reactions resulting from the minerals contained in the lake. This is thought to possibly be triggered by volcanic gas activity, but is more likely due to oxidation-reduction reactions.

The volcano stands at a height of 1,639 meters. It was last active in 1968 and is now considered extinct.

10 - Bubblegum Water: Lake Hillier

Off the south coast of Australia, there is a sight to behold in the form of bubblegum pink water. Lake Hillier is ten times saltier than the ocean, and contains microorganisms that produce red dye. Though scientists don't know the true reason behind the pink colour, they believe it is a combination of the salt content and microorganisms that dye it.

There are very few ways to reach Lake Hillier. The lake is surrounded by a rim of salt, sand, and a dense forest of paperbark and eucalyptus trees. Airplane scenic tours are the most common.

The length is 600 meters long and 250 meters wide. It lies very close to the Antarctic Ocean, separated only by a narrow strip of sand dunes and some vegetation.

The pink colour of this lake is permanent. When transferred to a container, the water does not change colour at all, remaining just as vibrant as it is in the lake. Despite the colour and high salt content, the lake is safe to swim in.

Previously, the lake was used to harvest salt. Now, this is no longer done, and it is mainly used for tourist purposes.

9 - Sea Creatures Galore: The Great Barrier Reef

The Great Barrier Reef, located off the coast of Queensland, Australia, is the largest coral reef system in the world. It is composed of over 3,000 reefs and stretches over 344,400 square kilometers.

The Great Barrier Reef supports many species, including many that are considered vulnerable or endangered. Apart from the many reef species, this reef system also contains 700 species of coral, 1,600 fish species, 134 shark and ray species, 30 dolphin and whale species, 6 of the 7 turtle species, 15 sea snake species, and 3,000 mollusk species. There are also thousands of plant species in the waters, and hundreds of birds that visit or nest on the island. Being the largest single structure made by living organisms, the Great Barrier Reef is so large that it can be seen from space!

The Great Barrier Reef Marine Park Authority considers the greatest threat to the Great Barrier Reef to be climate change. Increasing temperatures have caused the ocean to heat up, causing mass coral bleaching events to happen.

Coral bleaching occurs when coral polyps try to expel algae that get inside their tissues. They normally have a good relationship with the algae, with the algae providing them with up to 90% of their energy. With the ocean temperature increasing, algae populations increase. The corals overcompensate their expulsion of the algae and become more susceptible to disease and lose their main energy source.

Mass coral bleaching events happened in the summers of 1998, 2002, and 2006. It is expected that these events become an annual occurrence.