River rapids are classified according to their technical difficulty, established during normal flow periods. This difficulty may vary depending on the river flow rate. The following classification was established by the decree of May 4, 1995 from the Ministry of Youth and Sports.
Class I = easy:
Regular flow, regular waves, small eddies, simple obstacles.
Class II = moderately difficult:
(clear passage) irregular flow, irregular waves, moderate eddies, weak whirlpools and rapids, simple obstacles in the current, small drops.
Class III = difficult:
(visible passage) high irregular waves, large eddies, whirlpools and rapids. Rock blocks, small falls, various obstacles in the current.
Class IV = very difficult:
(passage not visible in advance, scouting generally necessary) large continuous waves, powerful rollers and rapids. Rocks obstructing the current, higher falls with hydraulics.
Class V = extremely difficult:
(scouting inevitable) extreme waves, whirlpools, and rapids. Narrow passages, very high falls with difficult entries and exits.
Class VI = limit of navigability:
(generally impossible) possibly navigable depending on water levels. High risks.