Difficulty of Czech and Slovak rivers is grouped to a couple of categories. In this country, we are using Alpen categories with 9 groups. Calm water has from ZWA (lake, dam), ZWB (a little running) to ZWC (soft running). You can find only one category ZW what is junction of all categories with calm water.

Whitewater has 6 groups: WW I (easy), WW II (a little hard), WW III (hard), WW IV (very hard), WW V (extreme hard), WW VI (very extreme hard). There is used for better adjustment sign + (high difficult) and - (less difficult).

Czech rivers are dependent on the water level. In the spring, we have a high water from snow, but we are dependent only on a rain during next months. You can mostly ship an upper part of the rivers only in spring or after heavy rain. It is recommended to consult with actual water level. Czech rivers have usually a narrow stone river-basin with amount rapids and sluices.