Paddling Ratings

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Paddling Difficulty Ratings for Canoeing, Kayaking, Paddleboarding, and Rafting Adventures on Rivers, Oceans, and Lakes

Adventure Nerds uses objective factors and the widely-used ISRD ratings to calculate the rating of paddling adventures across all Guide Notes. Each Guides Notes book includes an explanation for the Adventure Nerds paddling rating. The difficulty of rapids is highly subjective and depends on your experience, fitness, environmental conditions, equipment, group, and more. We suggest that you review the authors’ biography, learn about the location, and make decisions about the appropriateness of an adventure based on your experience level and current conditions. All ratings are based on ideal conditions and do not account for additional factors like wind, waves, weather, currents, river flow, or remoteness. Please read the American Whitewater Association’s ISRD rating scale for rapids, and learn about the environmental factors that may impact the difficulty of your adventure.

A Brief Explanation of ISRD Ratings

The International Scale of River Difficulty (ISRD) was created by the American Whitewater Association to standardize the assessment of rapids. You can read more about the difficulty classifications on their website. Although the ratings are commonly used, the rating system is based on subjective factors. Every river has a unique character, and paddlers may rate rapids differently. When possible, we advise checking multiple sources for ratings. Adventure Nerds ratings are based on the highest non-avoidable rapid.

Class A. Flatwater with no perceptible movement of water. Lake water.

Class I Easy. Moving water with no hazards and obvious obstacles that require little to no maneuvering to avoid. Self-rescue is possible.

Class II Novice. Moving water with small waves (<1 meter, 3 feet) in wide, clear channels. Some maneuvering may be required to avoid obstacles. Self-rescue is possible.

Class III Intermediate. Fast-moving water and rapids with larger waves (1-2 meters, 3-6 feet) and/or irregular waves that may be difficult to avoid. Advanced maneuvering is required to avoid obstacles, narrow channels, rocks, ledges, and strong currents/eddies. Large waves and strainers are typically avoidable. Self-rescue is possible but may require group assistance. Class III rapids are often recommended as the limit for experienced paddlers with open canoes on multi-day adventures.

Class IV Advanced. Powerful rapids that require precise boat handling. Rapids may require mandatory moves to avoid hazards and serious injury. Self-rescue may be difficult, and group rescue may require practiced skills.

Class V and VI Expert+. “Extremely long, obstructed, or very violent rapids which expose a paddler to added risk…rescue is often difficult, or impossible, even for experts.” Exact maneuvering is required to avoid hazards with major consequences. Class VI rapids have rarely been attempted and exemplify danger.

Factors That May Change The Difficulty Rating of Your Paddling Adventure

Environmental Factors

Remoteness. The remoteness of a paddling location does not change the mechanics of paddling, but it does impact the consequences of negative events. Time is a critical factor in rescues and evacuations, and remoteness extends the time to care. Rapids with easy access points and proximity to medical care have a different risk profile than rapids with limited access points or a significant distance from medical care.

Weather and Seasons. Hypothermia is a major risk for water-based activities. Air and water temperatures can dramatically impact your body’s ability to function. The consequences of submersion in winter and summer are different and should be considered when evaluating a paddling adventure plan. Rain, snow, heat, UV index, and air quality are examples of other weather factors that might impact your adventure.

River Flow. Rivers are dynamic and constantly changing. Every river has different low, medium, and high water levels. Damn releases, snow melts, rain, and droughts impact water levels. Low water levels may expose rocks or other hazards that make sections difficult or require portaging. High water levels and floods increase the speed of the water and may wash debris into the river and create unexpected hazards. High water levels can dramatically change the hydraulics of existing rapids and create new obstacles.

Wind. The friction of the wind blowing across the water creates waves. Wind also exerts forces on the exposed surface area of your boat and impacts your speed and handling. The following table has general guidelines for altering your perspective on the difficulty of a paddling adventure. If you are embarking on a paddling adventure at your maximum comfort rating, and the wind speed greater than the wind speed listed, you might want to reconsider your plans. These guidelines are highly dependent on your skills and experience.

Waves. Waves impact the stability of your boat, reduce your ability to efficiently move through the water, and can cause you to capsize. The following table has general guidelines for altering your perspective on the difficulty of a paddling adventure. If you are embarking on a paddling adventure at your maximum comfort rating, and the wave heights are greater than the wave heights listed, you might want to reconsider your plans. These guidelines are highly dependent on your skills and experience.

Current and Tides. The shape of the shoreline, wind, weather and the relative position of the sun, moon, and Earth determine the tides and currents. There are resources listed in Guide Notes for checking and forecasting tides. In some places, the change in tides is nearly imperceptible. While some locations like the Bay of Fundy in Nova Scotia have recorded tidal changes of 50 feet (15 meters) or more. Currents are controlled by tides, weather, and water density. Do yourself a favor and paddle with the current whenever possible; it is way more fun. Crosscurrents and opposing currents can dramatically impact your stability and ability to navigate where you want to go. If you are embarking on a paddling adventure at your maximum comfort rating, and the speed of the current is greater than the speed listed, you might want to reconsider your plans. These guidelines are highly dependent on your skills and experience.

Additional factors for portages. Along with the length and elevation change, the conditions of the portage trail can alter the difficulty of portage. Trail conditions can vary dramatically throughout the year. Examples of trail conditions that might change the challenge level of an adventure include accessing the trail from the water, finding the correct trail, bugs, rocks, overgrowth, and mud. A short portage with little elevation gain through a swamp has a different difficulty than the same length trail on a paved pathway. If the trail conditions are static (the obstacle always exists), we have taken these conditions into account for our ratings. If it is a dynamic factor (an obstacle that changes – like the presence of mosquitos), we have included these as notes in the description.

Logistical Factors

Total Distance. Complexity increases with the distance and travel time. Advanced planning for food, equipment, environmental exposure, and endurance are a few factors that make extended paddling adventures more difficult.

Gear Weight. The amount and distribution of weight impacts a boat’s performance and the difficulty of the adventure. Consider your boat’s weight limit, the portages, and environmental factors when packing for your adventure.

Human Factors

Personal Experience. Local knowledge, paddling experience, health, strength, endurance, and familiarity with equipment are a few factors that may change the adventure difficulty.

Group Size. Solo paddling requires unique skills and self-reliance. Groups provide options for physical and emotional support. However, additional people also create new complications. The relationships between group members and diverse personal characteristics will shape your adventure. A larger group will typically take more time to complete the same paddle as a comparable small group (see The Slinky Effect). High-performing groups may divide responsibilities and increase efficiency for some tasks. Novice group members may increase the time for planning and execution. Every group is different.

Group Time Estimator For New Groups

When new groups form, there is an adjustment period. Familiar short-duration activities like brushing teeth, cleaning dishes, and setting up tents can take a surprising amount of time, especially for novice paddlers. We recommend adjusting schedules to allow time for new groups to learn how to efficiently work together in a new environment.

Nate’s Formula: (time for solo activity) + (time for solo activity * number of times the group size doubles). Every time the group size doubles, add the time required for the solo activity to the base solo activity time. As experience increases, the time for a group to complete the task will decrease.
1 person = 5 minutes
2 people = 5 + (5 minutes * 1 [once]) = 10 minutes
4 people = 5 + (5 minutes * 2 [twice]) = 15 minutes
8 people = 5 + (5 minutes * 3 [thrice]) = 20 minutes