But absolute safety cannot be guaranteed. The main dangers of the sport are weather-related. In April, three months before the disaster in Switzerland in which 18 people died, a British woman was killed canyoning in Australia's Blue Mountains. She had not been wearing a crash helmet. Flash floods are considered to be a major hazard in many canyons.
Easy abseils can become tricky and take much longer than anticipated in pouring rain.
Hypothermia is a major risk, particularly for inexperienced canyonists who are left waiting in cold water for an abseil to finish. Deep ravines are often very cold places because sun-light is blocked out. Swimming and wading in cold water can tire out even the experienced in a matter of minutes rather than hours. The favourite locations for canyoning are in the Swiss, Austrian and French Alps, the Spanish Pyrenees and in Australia's Blue Mountains. Many companies have sprung up in recent years offering canyoning tours and introductory courses.