CentralNotice From Wikipedia, the free encyclopedia Jump to navigation Jump to search The examples and perspective in this article may not represent a worldwide view of the subject . You may improve this article , discuss the issue on the talk page , or create a new article , as appropriate. ( January 2019 ) ( Learn how and when to remove this template message ) Class III rapid at Canolfan Tryweryn , Wales. The international scale of river difficulty is an American system used to rate the difficulty of navigating a stretch of river, or a single (sometimes whitewater ) rapid . [1] The scale was created by the American Whitewater Association to evaluate rivers throughout the world, hence international in the title. [2] It should not be confused with the internationally used whitewater scale, which is published and adapted by a committee of the International Canoe Fe...