Canyonning is a non-competitive wilderness activity much like caving, but in the open air. It hasn't caught on that much in the UK (there are outdoor activity places that offer it as an activity, but no guidebooks published). This is starting to change with the first Canyon Guide assessments and canyon leadership courses being offered in 2011, but the emphasis is still on commercial ventures leading newcomers, rather than on traditional club activities the way other outdoor sports have developed. This seems to be leading to detailed information on canyons being treated almost as commercial secrets by the people who are doing the exploration - UK Canyon Guides has a guidebook section on their website, but only accessible to paid-up members. We deplore this attitude and encourage canyoners to write up their trips with rigging info for future reference. By contrast, the sport is very popular in mainland Europe, where bigger mountains, sunshine and (sometimes) warmer water make it both enjoyable and very photogenic (natural lighting makes photography much easier than in the dark). Guidebooks are readily available and local tourist associations are keen to publicise the activity and make safety information (including rigging information) widely available.
Personal equipment is very much the same as you would use for a rappelling through trip in Yorkshire (think Swinsto to Valley Entrance) - harness, cow's tail, claude loop, descender (one that works on double rope like a figure-eight). There are specialised versions of this kit available in Europe (for instance, harnesses which incorporate protection for your bum when sliding down rocks, helping to maintain the integrity of both harness and trousers). In warmer climates, clothing is often lighter than full caving gear - often shorty wetsuits, or gear similar to summer canoeing apparel. See our evolving Canyonning - Equipment page. For dry canyons, normal walking gear is OK, though some knee and elbow protection is useful on climbs and pitches. Most European trips involve at least some water - we've found that for open sunny canyons in the alps, thin wetsuit trousers and a kagoule with wrist (and maybe neck) seals make a fine combination. Canyons do vary from very open and sunny, with water that can largely be avoided on pitches, through to deep narrow, shady ravines with wet pitches, long swims and cold water - in these a full wetsuit and a buoyancy aid may be better. Often, boulder scrambling is interspersed with splashy pitches and deep pools (and some short pitches can be jumped into deep water - provided someone checks the pool first). There are canyons which wind down deeply with a real caving feel, only to emerge suddenly into dazzling sunshine, sometimes in stunning situations with fine views - swimming around in crystal-clear cool water part way down a 200m cliff is a unique experience!
Apart from a few trips in the UK, SOC members have been canyonning in mainland Spain, Majorca, the French Alps, Austria, the USA and probably several other places. Canyons in the desert southwest of the USA are often spectacular dry affairs cut through sandstone, with some risk of flash flooding, whilst others have deep cold water pools, even in summer. European canyons are far more likely to have permanent streams, but can also flood quickly, so care is always needed with the weather. Most recently, two summer trips to the alps (mostly Canoe Section members) have had the odd day canyonning and there's are trip reports from 2010 and 2011 with photos.
Not many years ago, canyonning was a new activity indulged in mostly by cavers and was not well-known. Participants often had to set up natural belays and abandon slings at the heads of pitches. It was prudent, particularly on longer trips, to carry quite a bit of rigging gear, perhaps even a bolting kit. In Europe, canyonning is now a sport on its own (with commercially led trips), no longer particularly associated with caving (though much of the gear is made by the same companies). There have been guidebooks available for a few years, and local tourist authorities now promote the sport (they'd never heard of it when we first started).
In Europe, many canyons are equipped with stainless steel bolts and chains which makes rigging quick and easy, with no need to leave any bits of tat behind. In the USA, much lower traffic and a wilderness ethic emphasises not bolting, and not leaving anything manmade behind - old school cavers will remember when SRT was all done on natural belays, so it is possible. Australians leave slings behind, but choose natural fibres which will rot away. As the sport is less well known in the UK, there are few routes that are fully equipped with bolted belays (and the outdoor centres which have equipped them keep quiet about locations), but, correspondingly, there is so much more waiting to be explored - learning to use natural belays when possible will make your trips quicker and more interesting as well as avoiding becoming stranded!
The system of canyonning grades in the UK is in its infancy (and not widely understood), and caving grades are not ideal. The grades you are most likely to encounter in Europe use the French system based on the same grades as those used in mountaineering. These cover activities in some very variable conditions, including extreme ski descents, so the grades are far from being "designed for canyons". These grades run from "Facile", through "Peut difficile", "Assez difficule", "Difficile" to "Tres difficile" (and beyond, in mountaineering), modified by a "+" or "-" for high and low in the grade. Some newer guidebooks may have started to use the more detailed numerical system sponsored by both mountaineering and caving federations. We've got an English version of this grading system (needs a little more work) which might be useful for giving grades to any UK canyons you explore. The American Canyoneering Association has a canyon-specific grading system which perhaps indicates what could be done and what sort of difficulties need considering, but it does seem very complex, and no-one else seemed to use it until UK Canyon Guides started to adopt it in 2011. They have adapted it a bit, but note a few Americanisms - "stemming" is what we would call "bridging". The Spanish grade canyons from 1-6, but have a special symbol ≈ to indicate routes which become significantly harder in high water.
In the guidebooks we've used, canyons graded Facile tend to involve only scrambling and maybe short hand-over-hand rope descents or jumps, with water which is mostly avoidable or not cold (or easily climbed out of after a jump). Peu Difficile have short pitches with relatively straightforward take-offs, no long swims, no big jumps and no pounding waterfalls. Harder grades take in longer pitches, more technical take-offs (and perhaps tyroleans to avoid water), harder climbs, swimming sections and colder water, but also allow for simply more of the same - more pitches, longer trips, harder walk-ins. At the top end of the trips in the area of the alps we most recently visited are things like the Rio Claretto with 46 short to medium pitches before the stream debouches down a 700 foot waterfall done in three drops. This is only Difficile and there are others up to TD which are technically harder but not as long (guidebook times run to about eight hours maximum but compare your own times on short canyons with the guidebook times - bigger and/or less experienced parties are a lot slower). In Majorca, the most famous canyon taken on Cavers' holidays (typically in winter when it's cheap) is Sa Fosca, with 36 pitches big enough to need a rope (or a careful jump), and several of the 6-12 hours it generally takes spent in total darkness in a stream a few feet wide and a thousand feet below the rim. This seems to get the modern French grade v3a4III.
There is scope to enjoy canyonning at almost any level, even multiday descents... but French postcards showing bikini-clad girls abseiling sunny waterfalls remind us that you don't have to be a hardman to enjoy the easier venues. Some canyons can indeed on odd occasions be extremely crowded with large led groups of complete novices - one of our 2011 trips in the Fournel Canyon found itself hacking past six French groups of up to twenty kids and adults, but on another day we had it to ourselves.