A rapid is a section of a river where it loses much altitude, causing the water current to become very rapid the flow very turbulent. Often the river will be shallow, with rocks sticking up from the surface. When the water splashes over and around the rocks, it mixes with air and takes on a white colour, forming whitewater.

The sports of canoeing and kayaking have a grading system for rapids (or a number of systems, varying among countries). Rapids may be classified as follows:

• Class 1 - no rapids, smooth flowing water
• Class 2 - some rough water
• Class 3 - whitewater but very safe for larger rafts
• Class 4 - whitewater for experienced rafters only
• Class 5 - whitewater for experts only
• Class 6 - impassable

See also rafting for a rafting grading system for rapids.

Even with such systems, the meaning and understanding of the word rapids, can vary enormously, depending on the perception, skill level, experience and bravery or foolhardiness of the paddler.

Also, some rivers with huge volumes of fast moving water may require little manouevering, but will pose serious risk of injury or death in the event of a capsize. Other, more technical rivers, may require great skill in negotiating through many rocks, but with low water flows may pose only a low level of danger.

Australia

In Australia, (from memory) the grading system varies from:

1. slightly disturbed water surface, no navigation effort required
2. quickly flowing water, some skill required to pick and follow a course
3. quickly flowing water, considerable skill required to pick and follow a course, definite risk of injury for an unskilled paddler
4. sub-extreme
5. extreme
6. probable death for all the very best and very lucky not sure

See Slso

• whitewater
• wild water