Uluru (Ayers Rock) - Australia

Uluru, also referred to as Ayers Rock, is a large sandstone rock formation in the southern part of the Northern Territory, central Australia. It lies 335 km (208 mi) south west of the nearest large town, Alice Springs; 450 km (280 mi) by road. Kata Tjuta (The Olgas) and Uluru are the two major features of the Uluru - Kata Tjuta National Park. Uluru is sacred to the Pitjantjatjara and Yankunytjatjara, the Aboriginal people of the area. It has many springs, waterholes, rock caves and ancient paintings. Uluru is listed as a World Heritage Site.

Uluru is one of Australia's most recognisable natural icons. The world-renowned sandstone formation stands 348 m (1,142 ft) high (863 m/2,831 ft above sea level) with most of its bulk below the ground, and measures 9.4 km (5.8 mi) in circumference. Both Uluru and Kata Tjuta have great cultural significance for the Aṉangu Traditional landowners, who lead walking tours to inform visitors about the local flora and fauna, bush foods and the Aboriginal dreamtime stories of the area.

Uluru is notable for appearing to change colour as the different light strikes it at different times of the day and year, with sunset a particularly remarkable sight when it briefly glows red. Although rainfall is uncommon in this semiarid area, during wet periods the rock acquires a silvery-grey colour, with streaks of black algae forming on the areas that serve as channels for water flow.

Kata Tjuta, also called Mount Olga or The Olgas owing to its peculiar formation, is another rock formation about 25 km (16 mi) from Uluru. Special viewing areas with road access and parking have been constructed to give tourists the best views of both sites at dawn and dusk.

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Mackenzie River - Canada

The Mackenzie River originates in Great Slave Lake, in the Northwest Territories, and flows north into the Arctic Ocean. It is the longest river in Canada at 1,738 km and, together with its headstreams the Peace and the Finlay, the second longest river in North America at 4,241 km in length. The Mackenzie and its tributaries drain 1,805,200 square kilometers. Its mean discharge is 9,700 cubic metres per second.

The large marshy delta of the Mackenzie River provides habitat for migrating Snow Geese, Tundra Swans, and Brant as well as breeding habitat for other waterfowl. The estuary is a calving area for Beluga whales.

The river is navigable for approximately five months of the year. It freezes over in October and the ice on the river breaks up in May. During the winter months, sections of the river are used as an ice road.

During the ice-free period the river is navigable over its entire length. Barge traffic from an intermodal hub at the railhead at Hay River serves much of the Western Arctic.

The Mackenzie (previously Disappointment River) was named after Alexander Mackenzie, who travelled the river while trying to reach the Pacific Ocean in 1789. In the Dene languages it is called Deh Cho.

The divide between the Mackenzie basin and the basin of the Yukon River to the west forms the central portion of the boundary between Northwest Territories and the Yukon.

In 2008, Canadian and Japanese researchers extracted a constant stream of natural gas from a test project at the Mallik methane hydrate field in the Mackenzie delta. This was the second such drilling at Mallik: the first took place in 2002 and used heat to release methane. In the 2008 experiment, researchers were able to extract gas by lowering the pressure, without heating, requiring significantly less energy. The Mallik gas hydrate field was first discovered by Imperial Oil in 1971-1972.

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Oasis in Morocco

Oases are formed from underground rivers or aquifers such as an artesian aquifer, where water can reach the surface naturally by pressure or by man made wells. Occasional brief thunderstorms provide subterranean water to sustain natural oases, such as the Tuat. Substrata of impermeable rock and stone can trap water and retain it in pockets; or on long faulting subsurface ridges or volcanic dikes water can collect and percolate to the surface. Any incidence of water is then used by migrating birds who also pass seeds with their droppings which will grow at the waters edge forming an oasis.

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The most dangerous beaches

A beach vacation usually conjures up images of lying on white sand relaxing not dicing with death but Forbes.com has come up with a list of the world's most dangerous beaches.

Strong currents and deadly jellyfish are among the dangers that spring to mind but the biggest fear is sharks, according to Stephen P. Leatherman of the International Hurricane Research Center & Laboratory for Coastal Research in Miami.

"But in reality, you've got a better chance at winning the lottery than getting bitten," he told Forbes.com, adding that there were only 112 incidents globally of shark bites in 2007.

Following is a list of the most dangerous beaches by category which was prepared by Forbes.com and focuses mainly on the United States.

1. Shark Attacks/Bites

New Smyrna Beach, Volusia County, Florida.

The were 112 incidents of shark-human "contact" in 2007, according to the International Shark Attack File released in March but only one resulted in a human fatality. New Smyrna, an inlet on the eastern coastline of Florida, had the most attacks, with 17 bites recorded.

2. Pollution

Hacks Point Beach, Kent County, Md./Beachwood Beach West, Ocean County, N.J.

According to the National Research Defense Council, an environmental action group, these two beaches had the highest percentage of samples exceeding U.S. health standards in 2006.

3. Jellyfish Attacks

Northern Australia

The coast of Northern Australia serves as a home to chironex fleckeri, also known as the box jellyfish, which has caused 60 deaths in the last 100 years, according the Center for Disease Control, Australia. While fatalities are rare, about 40 people are hospitalized each year in the Northern Territory. Last year, a 6-year-old boy died in the Tiwi Islands, north of Darwin.

4. Lightning

Florida

Florida tops off the list as the most dangerous spot for lightning, according to the National Oceanic and Atmospheric Administration. Between 1997 and 2006, there were 71 deaths caused by lightning in Florida, more than any other state. Popular beaches such as New Smyrna and Clearwater are often evacuated and then closed for days because of the threat of lightning.

5. Boating Accidents

Florida

Data by county or beach is not available, but according to the U.S. Coast Guard's Boating Safety Division, the state of Florida reported 633 boating accidents and 68 fatalities in 2006, the highest number of any state in the country with more people actively involved in boating in Florida.

6. Rip Current Drowning

Brevard County, Florida

In 2007, 10 people drowned in Brevard County due to the rip current alone, according to the United States Life Saving Association.

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