Fast moving water, ripples and small waves. Few obstructions, all obvious.
Straight forward rapids with wide clear channels evident without scouting. Rocks and medium sized waves easily missed by trained paddlers.
Rapids with moderate and irregular waves. Strong eddies and powerful currents, particularly on large volume rivers. Good boat control is required in tight passages and around ledges. Scouting is advisable. Rescue is possible.
Intense powerful but predictable rapids. May feature large unavoidable waves and holes or constricted passages demanding fast maneuvering under pressure. Scouting is necessary first time.
Difficult rescue may be possible.
Extremely long, obstructed or violent rapids which expose a paddler to above average danger. Drops may contain large unavoidable waves and holes. Rapids may continue for long distances between pools, requiring a level of fitness. Scouting is essential but difficult.
Difficult and painful rescue may be possible.
These runs exemplify extremes of difficulty and danger. For teams of experts only, at favorable water levels and after close study and taking all precautions. NO RESCUE POSSIBLE!
MAKE YOUR MOVE OR DIE!