Dangers include weirs, cold water and fast-currents
An environment group has urged children and teenagers to take extra care around water over the holiday break.
The Environment Agency said young people planning water activities should be aware of potential dangers.
These dangers include fast-currents, cold water, structures such as weirs and locks and unstable riverbanks.
Nick Gupta, agency spokesman, said 50 children under the age of 16 drown every year, with drownings the third most common cause of accidental death.
The agency has worked in partnership with the Royal Society for the Prevention of Accidents (ROSPA) to produce a water safety leaflet, to be distributed to primary and secondary schools in Wiltshire, Somerset and Gloucestershire.