Reading is fun – words envelop you in stories, they change your point of view, gift you with knowledge and plunge you into new worlds. But for all of the enchantment of words, reading books pales in comparison to the magic of reading whitewater.

Learning to read whitewater takes practice and experience – unlike words in books it is rare for a river feature to appear exactly the same on any two rapids – however there are some core principles that can help you understand the basics.

Test your whitewater knowledge here and read on after the quiz to learn more about those core river features.

↓ Take Bren’s whitewater Quiz ↓

[HDquiz quiz = “559”]

Did you nail the answers to my quiz? Either way – there is always more to learn about how a river works.

Core river features

Creeking and big water

Whitewater comes in many shapes and sizes but practically it can be separated into two groups; high volume and low volume. It’s all down to how the water interacts with the rocks of the riverbed and what they are made out of.

On a low volume river the water will be flowing around rocks, through the cracks in between rocks and occasionally thinly sliding over the tops of them. This style of whitewater is commonly called ‘creeking’.

On a high volume river the water will still be flowing around rocks but mostly it will be pumping over the tops of them. On a high volume river the water will twist, squeeze and explode in ways that are often not found on low volume rivers. This style of whitewater is commonly called ‘big water’.  


An eddy is formed where the flow is diverted by an obstacle like a rock or the river bank. Big eddies are easy to spot as you will be able to see a large mass of water that looks either still or slowly recirculating back upstream. On really big volume rivers there are often surging waves to be found in the eddies, crazy eh?

Eddy line

This is the place where the edge of the eddy meets the rivers flow. Water often gets distorted on an eddy line as it is pulled in two directions. On low volume rivers and eddy line will barely be wider than a kayak, on big volume rivers they can be over a boat length wide. The Indus river in Pakistan contains some of the scariest eddy lines that I have ever had to deal with.


Often forming on an eddy line, whirlpools look like the water draining from your sink down the plughole. A whirlpool in whitewater is an unstable thing and even though they may be exceedingly powerful, they will often soon lose their strength and dissipate – provided you have the confidence to ride it out and stay in your kayak. The volume in your kayak is more than a match for most whirlpools.


The tongue usually represents the deepest and cleanest line down a rapid, you will be able to spot its characteristic downstream-V.


A hole is formed as the water shoots over a rock, falls to the river’s floor, surges up and recirculates back upstream. The rate at which the water rises back up in a hole is usually much slower than that of a wave, which springs or shoots back up.

Holes can be friendly or unfriendly. Generally speaking a friendly hole will stand up tall, have a low drop-off angle and there will be space between the drop and the recirculating towback. Rarely will a friendly hole be river wide.

An unfriendly hole will have a much steeper drop-off angle, very little gap in-between the drop off and the recirculating water and the water that will recirculate back up stream slowly. Often the towback of a bad hole is very flat and doesn’t stand up. Generally speaking any hole with more than a foot of tow back is probably not friendly.


A wave is formed as water shoots over a rock, falls to the rivers floor and springs back up. The wave’s crest may break and tumble back upstream but primarily the water never quite manages to get steep enough to recirculate upstream. A wave is easy to spot as generally they will stand up tall and will be made up of of ‘green’ water. Often the initial drop-off is low angle, which generally encourages a friendly feature to form. Whitewater waves share characteristics with their ocean counterparts, except in the ocean the water stays still and the wave moves and on the river the water moves and wave stays still. Huge aerial freestyle tricks can be thrown on waves.


The most dangerous of river features – this is where water flows through or under a rock. The water passes through easily but large objects will not fit through quite so easily. Some siphons can be easily spotted especially at low water, some are underwater and invisible. A good way to spot a hidden siphon is to look for the amount of water entering a rapid and the amount of water exiting – if you cannot see where all the water is going, there is more than likely something insidious, see if you can see water being sucked down around rocks or exiting behind a rock – a sure sign of siphons.


When water flows under a rock but doesn’t pass all of the way through, that’s an undercut. Raging in size from an awkward jutting low boulder to large underwater cave. The flow of water that makes the undercut is often still moving downstream and if you hold on long enough you will be pulled downstream away from it. However they can most definitely still be dangerous and they have an unfortunate habit of collecting debris such as trees that can ensnare a kayaker.


Does at it says on the tin, the water curls over itself and looks like a barreling wave in the ocean, often times a curler will feed into a much bigger feature.

Cushion wave

When the water does not have enough volume to flow over a rock it may break on top of the rock and flow back upstream, this makes a cushion wave in front of the rock. Cushion waves are useful features, like bumpers in a pinball machine that can help you change direction or surf away from an obstacle.


One of the most beautiful river features! While waterfalls are big and easy to see from some angles of view, from other perspectives they can sneak up really quickly. As you travel downstream look at the terrain next to the river, if it is dropping off steeply then it is more than likely that a significant amount of gradient is being lost to a waterfall.

Enjoy spotting these features on your local river! Except siphons, I hope you don’t see any of those! – Bren

Thanks to Chris Eastabrook for contributing some of these thumbnail example images.