Whirlpools are ominous vortices with the power to suck nearby objects into a watery spiral. Take a look beneath the surface.

Fast-flowing currents in oceans and rivers constantly change direction. Whirlpools are phenomena that form when water moving in two different directions comes into contact with each other and interact in an unusual way. They can't continue to travel at the same speed and direction through each other, so they are forced to turn and swirl around each other. 

Depending on the volume of water and force of colliding waters, whirlpools can appear in different sizes. Some whirlpools form and disappear over a short period of time, while some water systems keep whirlpools for centuries, according to the Niagra Parks website. The larger and more dangerous whirlpools are called maelstroms. These hold the power to fatally engulf anyone who comes too close.

How to survive a whirlpool

Whirlpools aren't as destructive as they are portrayed in fiction, such as the whirlpool battle in Pirates of the Caribbean. However, they do pose danger to people and small boats, according to the book. Most people won't experience the entrapment of a whirlpool's force but for many, such as kayakers, it is useful to know how to survive one.

According to World Champion kayaker, Ken Whiting, you need to make sure to wear protective gear when entering the water, such as a life vest and helmet. These can protect you from the harsh currents surrounding whirlpools. If you see any signs of whirlpools, it is best not to enter the water at all. 

In the event of entering a whirlpool, you shouldn't move in the same direction as the water flow and should aim for the outer edge rather than the center. When in a boat or kayak, try to prevent the boat from filling with water. In some instances, the whirlpool can throw you back out, according to Smithsonian Magazine. 

The power of whirlpools can be difficult to predict by their appearance.

World-famous whirlpools

Saltstraumen

In Norway, south of the city of Bodø, a small strait has one of the strongest tidal currents in the world, according to World Atlas. Where Skjerstad fjord and Salten fjord link together, water can travel at 10 meters per second to create this giant whirlpool up to 32.8 feet (10 meters) wide and 16.4 feet (5 meters) deep. 

Old Sow

Formed in the waters between Deer Island and Moose Island in Canada, Old Sow is one of the largest whirlpools in the western hemisphere. It can vary in size, within a diameter of around 250 feet (76 meters). Usually, several smaller whirlpools surround it. 

Naruto

Between Tokushima and Hyogo in Japan, the tidal whirlpool Naruto can form up to 66 feet (20 meters) in diameter. Water enters the narrow Naruto strait at speeds of 12 mph during spring tides.

Corryvreckan

Located between two rocks off the west coast of Scotland, this whirlpool is produced by the uneven sea bed. Deep pits and basalt pinnacles increase the speed of the water that flows through. It is considered to be the third largest whirlpool in the world. 

Moskstraumen

In the Norwegian Sea, between Mosken island and the southern part of the island of Moskenesøya, is the second strongest whirlpool in the world. At its largest, it is about 160 feet (49 meters) in diameter.