How To Read Water When Paddling Rivers

Photo: Ben York/TandemStock

Unless you’re in waves or a current, flatwater paddling on oceans and lakes is relatively straightforward.

But that largely two-dimensional playing field changes when you hit the river, where dynamic features like eddies, waves and other hydraulics come into play with the water’s eternal quest for sea level. Following are a few tips for reading water and safely navigating the current downriver.

Know Your Takeout

Before launching, know where your takeout is located, and how to recognize it from the water. This will also help you estimate how much time your paddle outing might take. 

Paddle Within Your Limits

Even savvy whitewater paddlers know ahead of time what sort of waterway they’re undertaking. Don’t be caught off guard trying to negotiate a Class IV rapid on a section you thought was only Class II. (Rapids are rated on a scale outlined below from Class I to VI, with I being slow-moving flatwater and VI being technically unrunnable; until you can consistently roll your kayak or capably self-rescue in the event of a swim, you should probably avoid paddling anything above Class II.) 

Understand Eddies

Eddies are your friend. They’re areas of the river, often on the inside of corners and behind boulders and other obstacles, where the current is calmer and moving back upstream. Recognize them as areas of slower-moving water compared to the main current of the river. Always look for them, and use them to rest, relax, wait for others upstream, and plan your next move: Hint: Cross the eddylines with authority, leaning your boat into the eddy when paddling in and leaning downstream when paddling (called “peeling”) out. 

Straight into Waves

If you encounter a wave train, or series of waves, and are feeling uncomfortable, keep your boat straight and paddle. Having blades in the water aids stability and increases your momentum for punching through waves and holes.

Waves vs. Holes

Differentiating the two takes a dedicated and experienced eye. In general, waves are smoother-looking from above and less abrupt. Holes, or hydraulics, on the other hand, often have sharp horizon lines, hiding a recirculating hydraulic below that can flip and even hold boats (especially if you hit them sideways or with no momentum). If you find yourself hitting one unexpectedly, keep it straight and paddle downriver, keeping your paddle blades in the deep water below to help pull you out.  

Obstacles and Hazards

Strainers (i.e. downed trees) and lowhead dams are two of the most dangerous obstacles on the river. Scout ahead for them and avoid them at all costs (lowhead dams are marked by an abrupt, uniform horizon line spanning the river). Also beware of drifting into boulders and other obstacles by turning your boat at an angle and paddling away; if you do hit something, lean into it (not away), until you slide off.  

Follow the Tongue

At the head of a rapid, look for a smooth, green ramp or “tongue” leading into the rapid; that’s usually the deepest and least obstructed part, setting you up for the best line.  

Scout Any Horizon Lines

Your vantage is low from a paddlecraft, inhibiting your ability to see what’s downstream when the gradient picks up. If you’re in a craft that allows it (ie. raft, canoe, or inflatable kayak), try kneeling or standing up to get a better view. Pull over or eddy out and scout if you don’t know the rapid or can’t see a safe line. 

Know Deep From Shallow

Get practice recognizing sections of deep water from shallow, which can beach your craft. Look for subtle color and texture changes in the water ahead; deeper water will often appear darker, while shallow water is often marked by small ripples.

Safety Basics

If you swim in moving water, the first thing to do is try and relax. You should already be wearing a properly fitting PFD, appropriate footwear and clothing for the water temperature, and, if in whitewater, a helmet. Your best bet is proactive self-rescue: either swim back to your craft, right it and climb back on board (if in an inflatable or sit-on-top); or swim to shore. If in shallow water or rapids, assume the safety position of rolling onto your back with your feet up and facing downstream to ward off rocks, with your hands off to the side for maneuvering around obstacles. Warning: Never try to stand up in moving water past knee-high as it can result in a foot entrapment. 

Two kayakers looking over on the South Silver river in Northern California. Photo: Zach Leighton/TandemStock

River Terms 

Taking to the river? Below are a few essential terms to get you oriented. 


Location where you start the trip. 


Place where the trip ends. 


Running a car down to the takeout so you can return home afterward. 

Eddy: Region of slow- or even upstream-moving water in the river, often on the inside of turns and behind rocks. Paddlers often use these to rest, regroup and scout what’s downstream. 


Also known as a hydraulic, these are areas in the river, caused by underwater rocks, where the water recirculates back on itself, creating a seam that’s hard to escape.  

Wave Train

A series of waves in a river. 


The left or right side of the river as you look downstream—this orientation is how you should always direct others.


Moving at a diagonal, facing upstream, to get across the river without losing any ground. 

Eddy Turn

Paddling into an eddy, and letting its opposing current help turn your boat. 

Peel Out

Coming out of an eddy into the main current.

River Classifications 

Rapids are rated on a scale of I to VI, referred to as grade or class. A river’s grade also changes with the level of flow. Oftentimes the plus (+) or minus (-) sign is added to indicate if it is in the higher or lower end of the difficulty level. While a river section may be given an overall grading, it may contain sections above that grade or lower. Below is a summary of river classifications as presented by American Whitewater:

Class I - Easy

Fast moving water with riffles and small waves. Few obstructions, all obvious and easily missed with little training. Risk to swimmers is slight; self-rescue is easy.

Class II - Moderate

Straightforward rapids with wide, clear channels which are evident without scouting. Occasional maneuvering may be required, but rocks and medium-sized waves are easily avoided by trained paddlers. Swimmers are seldom injured and group assistance, while helpful, is seldom needed.

Class III - Moderately Difficult

Rapids with moderate, irregular waves which may be difficult to avoid and which can swamp an open canoe. Complex maneuvers in fast current and good boat control in tight passages or around ledges are often required; large waves or strainers may be present but are easily avoided. Strong eddies and powerful currents can be found, particularly on large-volume rivers. Scouting is advisable for inexperienced parties. Injuries while swimming are rare; self-rescue is usually easy but group assistance may be required to avoid long swims.

Class IV - Advanced

Intense, powerful but predictable rapids requiring precise boat handling in turbulent water. It may feature large, unavoidable waves and holes or constricted passages demanding fast maneuvers under pressure. A fast, reliable eddy turn may be needed to initiate maneuvers, scout rapids, or rest. Rapids may require "must make" moves above dangerous hazards. Scouting may be necessary the first time down. Risk of injury to swimmers is moderate to high, and water conditions may make self-rescue difficult.

Class V - Expert

Extremely long, obstructed, or very violent rapids which expose a paddler to added risk. Drops may contain large, unavoidable waves and holes or steep, congested chutes with complex, demanding routes. Rapids may continue for long distances between pools, demanding a high level of fitness. Eddies may be small, turbulent, or difficult to reach. Scouting is recommended but may be difficult. Swims are dangerous, and rescue is often difficult even for experts. Proper equipment, extensive experience, and practiced rescue skills are essential.

Class VI - Extreme

Runs of this classification are rarely attempted and exemplify the extremes of difficulty, unpredictability and danger. The consequences of errors are severe and rescue may be impossible. For teams of experts only, at favorable water levels, after close personal inspection and taking all precautions. After a Class VI rapid has been run many times, its rating may be changed to an appropriate Class V+  rating.

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.