The Canary Islands are one of Europe's best winter rock-climbing destinations and one of its least crowded: volcanic rock, bolted sport routes across the full range of grades, dry sunny days from October to April, and crags you can often have to yourself on a Tuesday in January. Tenerife and Gran Canaria carry the great majority of the developed climbing; the smaller islands have scattered crags and a good deal of loose rock.

If you have never climbed, the short version is this. Almost all climbing here is sport climbing — routes with permanent steel bolts drilled into the rock, which you clip a rope into as you go up. You need a partner, a rope, a harness, shoes and quickdraws, or you can hire a qualified guide who brings all of it and teaches you as you go. There is very little of the traditional gear-placing climbing that British climbers grow up with, and the rock type here is unforgiving of it.

The season is the mirror image of northern Europe's. When Wales and the Peak District are wet and freezing, the Canaries are dry and about twenty degrees, which is why you will hear German, Polish and Czech spoken at the crags all winter.

What you are climbing on

Two rock types matter, and they climb completely differently.

Basalt is the dark, dense lava that built most of the islands. Where it cooled slowly it cracked into hexagonal columns, and columnar basalt gives long vertical crack lines and sharp incut edges. It is grippy, it is hard on the fingertips, and where it has weathered it can be brittle. Trachyte and phonolite, the paler and more silica-rich volcanic rocks, form the compact faces and pocketed walls that carry a lot of the harder sport routes — the surface is often peppered with small holes and blobs where gas bubbles and crystals sat.

Alongside both you will find ignimbrite and welded tuff, the compacted ash-flow rock that makes up much of the Canarian interior. It can be superb and it can be horrible, crumbling under a foot without warning, sometimes within the same route — the single biggest adjustment for climbers arriving from granite or limestone. The geology of how these islands were built explains most of it.

Volcanic rock ages badly in the sun and salt. Bolts corrode faster here than in a European mountain range, and old kit on unrefurbished routes has failed. Look at what you are clipping: shiny stainless steel and a modern hanger is fine, a rusting expansion bolt of unknown age is not. Back up anything you do not like, and treat old fixed gear at abandoned crags as decoration.

Tenerife: Arico

The Barranco de Arico, in the dry south-east of Tenerife, is the most developed climbing area in the archipelago and the reason most visiting climbers pick the island. It is a deep ravine with walls on both sides, several hundred routes, and sectors facing in enough directions that you can chase shade in September and sun in January.

The rock is largely a compact volcanic face with pockets and small edges, the routes are mostly single-pitch and well bolted, and the grade spread runs from comfortable beginner territory well into the hard end. It is close to the motorway and to the southern resorts, which makes it an easy day from Los Cristianos or Costa Adeje — around half an hour in a car.

Arico sits partly within a protected natural area and access arrangements have been negotiated rather than assumed. Some sectors have had seasonal restrictions for nesting birds, and a few have been closed outright at times. Check the current situation with a local club or shop before you drive out; the picture changes and printed guidebooks go out of date.

Tenerife: Las Vegas and the rest

Las Vegas, above Granadilla de Abona in the same southern belt, is the other Tenerife crag visiting climbers name. It is smaller than Arico, generally steeper, and it holds a good concentration of routes in the middle and upper grades on pocketed rock. It gets sun for much of the day, which makes it a winter venue rather than a summer one.

Beyond those two, Tenerife has a scatter of smaller developments: crags around the Teno massif in the north-west, bouldering near the coast, and high routes in the national park under Teide, where the altitude and cold change the game entirely. Teno and the Teide caldera are both protected landscapes with rules that apply to climbers as much as to walkers, and some island climbing is deliberately not publicised because access is delicate.

Gran Canaria: Ayacata and Sorrueda

Gran Canaria's climbing is concentrated in the mountainous centre and the southern valleys, and it has a different character — bigger, wilder, more mountain than crag.

Around Ayacata, the village high in the interior below Roque Nublo, there are bolted walls and slabs at altitude with genuinely spectacular surroundings. It is cool up here — around 1,300 metres — so it works in summer when the coast is too hot, and it can be genuinely cold and cloudy in winter. Bring more layers than you think.

Sorrueda, in the valley above the reservoir near Santa Lucía de Tirajana, is the warm-weather counterpart: a lower, drier, sunnier venue with a good spread of sport routes and a short walk-in. Between the two you can climb on the island in almost any month by choosing altitude. There is also climbing around the Tamadaba region and a number of crags in the western barrancos.

The famous monoliths are a different matter. Roque Nublo and Roque Bentayga were sacred to the pre-Hispanic Canarians; climbing on them is restricted. Do not assume that a rock you can see from the road is a route.

The season, and why it is upside down

Winter is the main season. October to April gives reliable dry weather and daytime temperatures usually in the low twenties at sea level. High summer is climbable, but the low crags are brutal: direct sun on dark volcanic rock takes the surface well past comfortable, and the friction goes with the heat.

Three weather features are worth knowing. The calima, the Saharan dust haze, coats rock with fine grit and ruins friction for a day or two after it clears. The north of every island is wetter than the south, so a rained-off morning in Puerto de la Cruz does not mean a rained-off day at Arico. And the trade wind can make an exposed crag unpleasant at a perfect temperature. Our overview of how the islands' weather actually works covers the north-south split, which matters more here than the month does.

Guides, clubs and getting started

If you have never climbed, or you have climbed indoors and want to try real rock, hire a guide. There are qualified instructors and small operators on both Tenerife and Gran Canaria running half-day and full-day sessions with all equipment provided, usually for one to four people. A half-day introduction is enough to get an adult up several routes and to learn to belay. Rates vary by operator and group size and we are not going to quote a figure that will be out of date; ask two or three and compare what is included.

Check that whoever you book holds a recognised qualification — a Spanish national mountain-guide or climbing-instructor certification, or an international equivalent — and carries public liability insurance. Ask directly. Experienced climbers should find the local club or the specialist shop before the crag: they hold the current access information and the honest opinion of which sectors have been rebolted. Topos age well; access notes do not.

Fly with your rope and hardware in hold baggage — harness, quickdraws and belay device will not pass through cabin security, and a rope is heavy enough to matter for your allowance. Shoes and chalk bag in hand luggage is the usual compromise. Chalk itself can attract questions at security, so keep it in an obvious climbing chalk bag rather than a plastic pouch.

Kit for volcanic rock

Bring what you would take to a sport crag anywhere, with a few adjustments for the rock:

Access, protection and not ruining it

A large proportion of the Canarian landscape is protected in one form or another: four national parks, numerous rural parks, nature reserves and special bird protection areas. The rules are real and enforced, and climbing access at several crags exists because local climbers negotiated it, not because there is a right to it.

In practice: do not bolt new routes without talking to the local community; respect seasonal closures for nesting raptors, the most common restriction; park where the signs allow and not across a farm track; carry everything out, tape wrappers included; and do not climb on or near archaeological sites, of which there are more here than is obvious. The pre-Hispanic Canarians used caves and rock shelters extensively, and their sites are legally protected.

Where to base yourself

For Arico and Las Vegas, the southern Tenerife resorts are the practical choice — everything is within forty minutes of the airport — though the towns themselves are not climbers' villages. A quieter alternative is one of the rural houses inland, nearer the rock and cheaper than the coast. On Gran Canaria, staying in the mountains at Tejeda puts you within twenty minutes of the high crags and in one of the loveliest villages on the islands; the south suits Sorrueda and the rest of a family holiday. A hire car is effectively compulsory, and car hire in the Canaries is cheap by European standards.

Before you go

The Canaries will not give you the scale of Chamonix or the polish of Kalymnos. What they give you is a four-hour flight from the UK to a crag where it is twenty-two degrees and dry in February, with a beach half an hour away for the rest day and a bill at the end of the week that a mainland trip would struggle to match.

Two final things. Check your travel insurance actually covers rock climbing — many standard policies exclude it, and the question of what island cover should include is worth five minutes before you book. And build a rest day in that is not a rest day wasted: the walking here is superb, and the trail network will take you places the crags never will.