by Frances Stanford

Created on: September 27, 2008   Last Updated: December 14, 2009

White water refers to rivers that contain rapids. Some rivers are easy to navigate and are perfect for beginners. Others present a challenge even to the veterans in this sport. In order to make it easier for participants to know which rivers are easier to navigate than others, the International Scale of River Difficulty is the system used for grading white water. This scale helps to rate the safety of a river or even one rapid in a river. It is designed as a guide to the technical difficulties you will encounter when riding the rapids and the skill level you need to navigate this water safely.

There are six levels in this classification system, but the levels are not fixed. Within each level there are rapids that are easier or harder than the others. For example, you can have a hard grade 3 and an easy grade 4. A river can be assigned a number with a plus or minus sign after it to denote whether it is easy or hard and the grade of the river changes with the flow of the water. This means that a river can have a different grade at different times of the year.

CLASS 1
This grade refers to a river that is easy to navigate. The rapids and the waves are small and there is a clear passage through them. When white water rafting a river with this classification, you will not find any serious obstacles around which you may have difficulty navigating.

CLASS 2

A river with this classification is rated as needing a medium level of skill in navigating white water. Although the passages are clear, there are some difficult rapids. In addition to being experienced in navigating this type of river, you do need to have a well-equipped boat and suitable equipment.

CLASS 3

The class three rivers are difficult. You will encounter many high rocks and high waves. There is likely to be many eddies on this type of river. The passages are narrow and will require expertise in manoeuvring around the obstacles. You do need a skilled boat operator for such a river and a scout to inform you of upcoming rapids and obstacles.

CLASS 4

A river with a Grade 4 rating is very difficult. The rapids are long and the waves are numerous and very high. Rocks are irregular and dangerous and the boiling eddies will also pose a challenge. The first time you navigate this river, you do need to scout it first to determine the best passages. You will need to be skilled in manoeuvring around obstacles and you definitely need a powerful boat.

CLASS 5

With the long and sometimes violent rapids you will encounter on a river with this rating, this is an extremely difficult white water experience. There seems to be no end to the rapids and there are many obstructions in the river. Sometimes there are big drops and the current is extremely strong. To navigate this river, you do need to be very skilled in white water rafting and you need to take all the safety precautions you possibly can.

CLASS 6

Rivers with a designation of Grade 6 are unnavigable.

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