Machu Picchu, Peru

Located on a mountainous area above the Urubamba Valley, Machu Picchu is a pre-Colombian Inca site and regardless of whether you have an interest in history or not, can make you stop and stare in sheer awe. Built initially in the middle of the 15th century, Machu Picchu was said to have been inhabited for around 100 years before it became uninhabited and went uncovered for over 3 centuries, until Hiriam Bingham, a Yale lecturer, rediscovered the site in July 1911.

The Eye of the Sahara, Mauritania

Formally known as the Richat Structure, the Eye of the Sahara is a much more appropriate name. This mysterious blue eye has puzzled scientist since the first space flights, when astronauts noticed it looking back at them. Space shuttles use the 50 km-wide feature as a landmark even today, it is so clear in the middle of the barren Sahara desert. Researchers now believe it is a "symmetrical uplift", essentially an area that rose up as hard quartz while softer rock and sand was eroded from it.

GREAT BLUE HOLE - BELIZE

Found on both land and in the ocean throughout the Bahamas and the national waters of Belize are deep circular cavities known as Blue Holes which are often the entrances to cave networks, some of them up to 14 kilometres in length. Divers have reported a vast number of aquatic creatures some of which are still new to science. In addition, they’ve recorded chambers filled with stalactites and stalagmites which only form in dry caves. For the explorers this was proof that at one time, nearly 65,000 years ago, when the world was in the grip of the last major ice age, the sea level of the Bahamas was up to 150 metres lower than it is today. Over time the limestone of the islands was eroded by water and vast cave networks created. When sea levels rose again about 10,000 years ago some of these collapsed inwards and the Blue Holes were formed.

Puerto Princesa Underground River (Philippines)

The Puerto Princesa Subterranean River National Park is located about 50 km north of the city of Puerto Princesa, Palawan, Philippines. It features a limestone karst mountain landscape with an 8.2 km. navigable underground river. A distinguishing feature of the river is that it winds through a cave before flowing directly into the South China Sea.

It includes major formations of stalactites and stalagmites, and several large chambers. The lower portion of the river is subject to tidal influences. The underground river is reputed to be the world's longest. At the mouth of the cave, a clear lagoon is framed by ancient trees growing right to the water's edge. Monkeys, large monitor lizards, and squirrels find their niche on the beach near the cave.

Sailing Stones, Death Valley, USA

This mysterious and ghostly phenomenon occurs at Racetrack Playa, Death Valley which is a fitting location! The stones travel long distances without any human or animal help! It seems as if they just lift themselves up and scoot along, making a trail or groove in the rock surface as they travel. Scientists' best guess as to why this happens at present is that wind at the level of the stones causes them almost to hydroplane. Sometimes they turn left or right, and other times it looks like two stones are racing each other. They only move every three or four years and the grooves take some time to build up. Definitely a wonder of the world!