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About Whitewater Rafting

River Rafting

For an adventurous vacation nothing offers thrills like the wild and scenic Tuolumne River or the North Fork of the Stanislaus river. Join a licensed rafting company with guides that are familiar with running a river and learn some terms assassinated with this sport listed below.


International Scale of River Difficulty
Class I Easy – Waves small; passages clear; no serious obstacles.
Class II Medium – Rapids of moderate difficulty with passages clear. Most open canoeists should never tackle anything tougher than class II.
Class III Difficult – Rapids are longer and rougher. Waves numerous, high, irregular; rocks; eddies; rapids with passages clear though narrow, requiring expertise to maneuver; scouting is usually needed. Requires good operator and boating equipment.
Class IV Very Difficult – Rapids are generally longer, steeper and more heavily obstructed. Waves are powerful, irregular; dangerous rock; boiling eddies; passages difficult to scout; scouting mandatory first time; powerful and precise maneuvering required. Demands expert boatman and equipment.
Class V Extremely Difficult – Long and violent rapids, following each other almost without interruption; riverbed extremely obstructed; big drops; violent current; very steep gradient; close study essential, but often difficult. All possible precautions must be taken.
Class VI or U Unrunnable
Whitewater Rafting Terms
Current Moving water, not a measurement
Gradient Measured in feet of elevation loss per mile of river. Tells the “steepness” of a river.
High Water River flow is above an expected average.
Hole, Hydraulic Where water flowing over an obstacle flows down, then back onto itself.
Eddie Water flowing upstream behind a rock or other obstacle. Eddies often provide a safe place to get out of the current.
Eddie Line, Eddie Fence Where the water flowing upstream passes the water flowing downstream.
Flow The amount of water passing a point in the river, measured in Cubic Feet per Second (CFS).
Laterals A wave or hole peeling off an obstacle at an angle.
Low Water River flow is below an expected average.
Passage The path between two obsticles or between each rapid
Put-In Where a river trip begins.
Pool-Drop A type of river in which rapids are separated by calmer pools of water, often more forgiving than continuous gradient rivers.
Rapid Where the water churns it is either shallow, the flow is constricted, or the river has a steeper section and those are the rapids.
River Right The right side of the river when facing downstream.
River Left The left side of the river when facing downstream.
River Rating A measure of the difficulty of a rapid or a river on a scale from I-V.
Run The section of river that a boat can float through.
Standing Wave, Haystack A wave in a river formed by obstacles on the river bottom, where the wave stands still relative to the bank.
Strainer, Sieve Where water can flow through but a boat cannot, making it a dangerous place to get stuck.
Take-Out Where a river trip ends.