There are a number of possible routes to the summit - none of which are particularly well defined. The best approach (in my humble opinion) is probably from Dyffryn Nantlle. Park somewhere along the B4418 and make your way, via a choice of pathways, onto the ridge that leads to Mynydd Mawr's sub-summit Foel Rudd, which is marked by a medium sized cairn. Then bare westwards along the broad ridge, skirting the edge of Crag y Bera, until you reach the summit proper. This is marked by a low circular cairn.
Two scrambles have been described on the mountain, one on Craig Cwm Du and the other on Craig y Bera. Both crags have a reputation for loose and friable rock, therefore perspective scramblers should be as adept at judging the quality of rock as they are at scrambling itself.
Sentries Ridge (Grade 2 or 3)
This route takes the huge buttresses and pinnacles of Craig y Bera. It begins around halfway along the crag and takes a more or less direct line up a prominent and pinnacled ridge, which gradually becomes steeper the higher one climbs.
Bear Buttresses (Grade 2/3)
A intimidating route, which begins difficultly but on good rock and follows a series of gendarmes and ribs to easier, but less stable, scrambling above. Difficulties can be avoided, but only be devious and obscure means. The crux, although not technically difficult, is the precarious ascent of Bear Tower near the end of the route.
Due to its slightly detached position and consequent long approaches, combined with tales of dubious rock and historical access issues, Mynydd Mawr has never been as popular with climbers as it perhaps should. The mountain's climbing is split between three areas – Craig Cwm Du in the north, Castell Cidwm in the east and finally, Craig y Bera in the south.
Climbs are listed from left to right, and are graded and rated with the aid of the Climbers’ Club Guide to Cwm Silyn and Cwellyn (Eifionydd), so for full descriptions, please refer to this book.
Routes are graded using the British Adjectival Grading System. Technical grades are generally only given to climbs graded adjectivally as Severe (S) or above. A conversion table of international climbing grades by SP member Corax is available HERE! Bolting is strictly prohibited on the crags listed here.
Craig Cwm Du
Craig Cwm Du occupies a dark and quiet corner on the mountain's northern flank. The crag's routes have a strong mountain character and were once popular with the pioneering climbers of the Edwardian era. Unfortunately much of the rock is quite friable and loose and it has since fallen from grace.
Perched above the north-western shore of Llyn Cwellyn are the crags of the Castell Cidwm area. With the exception of Craig Cwm Bychan which is located just to the north, all of the routes are on Castell Cidwm itself and are split between its three buttresses, namely Craig Planwydd, the South-East Face, and the North-East Buttress. The crag is home to what is undoubtedly the greatest concentration of difficult routes in the Cwllyn/Nantlle Area, many of which are of a splendidly high quality.
Craig Cwm Bychan
Craig y Bera
Probably the most popular of Mynydd Mawr's crags, Craig y Bera is a vast crumbling assortment of forlorn gullies and buttresses on the mountain's southern flank.
Clogwyn y Garreg
This little mini-mountain is located just to the south-east of Craig y Bera. It sits just above Llyn Dywarchen and is home to a good number of easily accessible single pitch routes. Historically, climbing has not been permitted here, but since the CRoW Act (2000), climbing is now allowed.
Because of Mynydd Mawr’s low altitude and proximity to the sea, good winter conditions are rare. Nevertheless, a handful of routes have been recorded on Craig Cwm Du.
Mountain ConditionsThis colourful little box below displays the weather forecast for Caernarfon, which is located just to the north-west of Mynydd Mawr. Remember that Caernarfon is situated at around sea level, while the mountain's summit reaches 689 metres. This means that when looking at temperature the adiabatic lapse rate must be taken into account which in Wales is a drop in temperature of between 0.5 and 1°C per 100m in altitude. Exposure and wind speed can also significantly lower temperatures.
When to Climb and Essential GearThe most reliable conditions are in the summer. The gear needed depends entirely on the routes you plan to do. A hike will require all the gear normally require for a hike in Wales, remember this Snowdonia so be sure to pack full waterproofs. Easier scrambles and rock routes will only require a moderate rack, while longer harder routes will require a full rack with a good compliment of cams. A singe 60 metre rope should serve well on most routes, however, twin or double ropes would be a wise choice for the harder stuff.
Getting ThereMynydd Mawr (SH 539 548) is located on the north western edge of the Snowdonia National Park, just to the west of the park’s main attraction – Snowdon (SH 609 544). The best access is off the A4085 which runs between Caernarfon (SH 481 629) in the north and Beddgelert (SH 589 482) in the South. It would take a long time to try and explain all the different approaches to this road, so I would suggest consulting Google Maps or equivalent for further instructions.
Castell Cidwm (SH 550 554) can be approached directly from the A4085 by parking along the road near Planwydd (SH 568 539) and then following the path along the western shore of Llyn Cwellyn to the crag’s base. Craig Cwm Du (SH 537 550) can also be reached directly from the main road by parking around Betws Garmon (SH 546 563) and following a public right of way through the forest and into Cwm Du.
If you plan to ascend the mountain via the Foel Rudd ridge, or climb at Craig y Bera or Clogwyn y Garreg then you will need to turn off the A4805 and onto the B4418 at Rhyd Ddu (SH 659 529), which will take you to the small car park at Llyn Dywarchen (SH 559 533).
Red Tape and AccessNo red tape here!
Although unlikely it's worth checking the countryside access map provided by the Countryside Council for Wales (CCW) regarding whether or not any restrictions on movement in the area are in place.
Countryside Access Map
For climbers, hill walkers and mountaineers, the British Mountaineering Council (BMC) runs a Regional Access Database, which holds mountain/crag specific information on matters of conservation and access, including issues such as nesting restrictions, nature designations and preferred parking.
Regional Access Database
If you are in any doubt about any particular access arrangement, or need to report an incident, you should contact your local BMC Access Representative or the BMC Access Officers for Wales: Elfyn Jones.
Camping and AccommodationThere’s an almost unlimited supply of accommodation within the Snowdonia National Park so it would be inappropriate to list it all here. For budget accommodation it’s worth checking out some of the following sites:
Youth Hostel Association in Wales
Independent Hostel Guide
Campsites in Gwynedd
There are a number of YHA hostels in the area, the nearest of which is the Snowdon Ranger in Rhyd Ddu. The Plas y Brenin National Mountain Centre in Capel Curig also has a bunkhouse, and its own indoor climbing wall if you’re still feeing energetic after your day in the mountains.
Government Bodies and Official Organisations
Snowdonia National Park Authority
Council for National Parks
Association of National Park Authorities
Conwy County Council
Gwynedd County Council
Powys County Council
Countryside Council for Wales
Forestry Commission Wales
Royal Commission on Ancient & Historical Monuments in Wales
Gwynedd Archaeological Trust
The National Trust
Hiking, Climbing and Mountaineering Organisations and Companies
British Mountaineering Council
The Climbers Club
Plas y Brenin National Mountain Centre
Mountain Weather Wales
Weather from the Met Office
Weather Channel UK
North Wales Tourism Partnership
Local Information from Gwynedd.com
Local Information from Snowdonia Wales Net
North Wales Index
Official Nantlle valley Website
Welsh Public Transport Information
Uk Train Timetable
Youth Hostel Association in Wales
North Wales Campsites
Maps and Guidebooks
Harvey Map Services
Climbers Club Guidebooks
North Wales Bouldering
Mid Wales Climbing
Cordee Travel and Adventure Sports Bookshop
Wildlife and Conservation
Joint Nature Conservation Committee
North Wales Wildlife Trust
Royal Society for the Protection of Birds
Welsh Language Board
Cymdeithas yr Iaith Gymraeg Welsh language pressure group
Cymuned Welsh language pressure group
Yr Urdd (Welsh Youth Association)
Welsh-English / English-Welsh online translator
Welsh-English / English-Welsh Online Dictionary
Welsh-English / English-Welsh Online Lexicon