Weird and Wonderful of Nature: Rivers and Lakes

Tidal bores are formed when the front of the incoming tide forms a wave or series of waves that travels up a river against its direction of flow. This phenomenon occurs in several dozen locations around the world, but by far the largest and most spectacular happens in the Qiantang river, China, where it can form a massive wave of water up to 9m (30ft) high and traveling upstream at up to 40km/h (25mph). The bore is so dangerous that it is thought only a handful of people have been able to surf it.

Largest Crater Lake

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Lake Toba, on the Indonesian island of Sumatra, is the site of a supervolcanic eruption around 75,000 years ago that was probably the largest anywhere on Earth during the last 25 million years. The crater formed by the eruption is now filled with water that makes Lakes Toba, which is around 100 km (60 miles) by 30 km (18 miles) in extent, and 505 m (1,650 ft) deep at its deepest point.

Largest Desert Lake

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Lake Turkana in the Great Rift Valley, Kenya, has a surface area of 6,405 km² (2,472 miles²) and an average depth of 30.2 m (99ft). It is the fourth largest salt lake in the world and is fed by the Omo, Turkwel and Kerio rivers. There is no outflow from Lake Tukana and the only method of water loss is by evaporation.

Largest Tropical Lake

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With a surface area of around 68,800 km² (26,563 miles²), Lake Victoria is the biggest lake in the world that lies within the tropics.  Containing some 2,750 km3 (659 miles3) of water, it is ranked as the seventh largest freshwater lake in the world. It is the main source of the Nile, the longest river. 

Saltiest Lake

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Don Juan Pond in Wright Valley, Antarctica, has such a high salt content that it remains a liquid even at temperatures as low as-53°C (-63.4°F). At its saltiest, the lake’s percentage of salt by weight is 40.2%, compared to 23.1% in the Dead Sea and a 3.38% average in the world’s oceans as a whole.

Greatest River Flow

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The Amazon river in South America has the greatest flow of any river, discharging an amazing average of 200,000 m3/sec (7,100,000 ft3/sec) into the Atlantic Ocean, which increases to more than 340,000 m3/sec (12,000,000 ft3/sec) in full flood. The lower 1,450 km (900 miles) averages 17m (55ft) in depth, but the river has a maximum depth of 124m (407ft). The Amazon is fed by over 1,000 tributaries and its flow is 60 times greater than that of the Nile. The Amazon accounts for about 20% of all the fresh water that drains into the world’s oceans.

Largest Waterfall (Vertical Area)

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Victoria Falls, on the Zambezi river between Zimbabwe and Zambia, is neither the tallest not widest in the world, but it is the largest by vertical area. Being 1,708 m (5,604ft) wide and 108m (354ft) high, it creates a sheet of falling water with an area of around 184,400 m² (1,984,000 ft²)

Largest Ephemeral Lake

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Like Lake Turkana, Lake Eyre-which is located in the lowest point in Australia-is an example of an endorheic system. It usually contains little or no water but occasionally floods due to heavy monsoon rains. In 1974, the greatest flooding of this salt flat basin created a temporary inland sea with an area of around 9,500 km² (3,600 miles²).

Deepest Hypersaline Lake

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The Dead Sea on the Israel-Jordan border is the deepest hypersaline (very salty) lake in the world, with a maximum depth of 378m (1,240 ft). The Dead Sea has an average salinity of more than 8.5 times that of Sea water. Dead Sea mud is believed by many people to have healing properties when rubbed on to the skin (right).