4.7
(6)
803
runners
42
runs
Jogging around Tanygrisiau Reservoir offers routes through a landscape shaped by the rugged Moelwyn Mountains and the area's industrial heritage. The region features waterside trails, views of waterfalls, and remnants of the slate-quarrying industry. Joggers can experience varied terrain, from relatively flat reservoir paths to more challenging mountain ascents, all set within Snowdonia National Park. The fluctuating water levels of the reservoir, part of a pumped storage system, add a dynamic visual element to the surroundings.
Last updated: May 11, 2026
5
runners
7.68km
01:13
480m
480m
Hard run. Very good fitness required. Mostly paved surfaces. Suitable for all skill levels.
9
runners
10.8km
01:11
200m
210m
Moderate run. Good fitness required. Mostly paved surfaces. Suitable for all skill levels.

Sign up for free
8
runners
8.99km
01:03
230m
230m
Moderate run. Good fitness required. Mostly paved surfaces. Suitable for all skill levels.
7
runners
13.2km
01:41
430m
430m
Hard run. Very good fitness required. Mostly paved surfaces. Suitable for all skill levels.
6
runners
7.73km
00:55
220m
220m
Moderate run. Good fitness required. Mostly paved surfaces. Suitable for all skill levels.
Get access to more routes and recommendations from other explorers.
Sign up for free
Already have an account?
Our route recommendations are based on thousands of hikes, rides, and runs completed by other people on komoot.
Start today with a free account
Your next adventure awaits.
Login or Signup
Cwmorthin Slate Quarry is an impressive area, a magical hanging industrial valley above Tan y Grisiau that highlights Wales' industrial heritage with its massive works and ruins. It was in operation between 1810 and 1939 and has five different underground levels which were serviced with extensive trackways and machinery. Many of the surface buildings, such as the slate mills, can still be seen. If you are a photographer, this is the place to come in the early summer light or the cold winter mist.
0
0
In my opinion the best way to view the damn is be traversing the ridge of Craigysgafn from Moelwym Mawr to Moelwym Bach. Allowing you to take in the damn and surroundings area from many different vantage points
0
0
The long abandoned Barracks and Mill buildings of Rhosydd Quarry in the Moelwyn mountains of North Wales on a changeable day last September. A break in the heavy cloud allowed a burst of sunlight through that lit up the shiny slate rubble to make it look a bit like water. The dark buildings stood out against the lower slopes of Foel Ddu.
0
0
The spartan barracks at Rhosydd, a hard place to live and work, not far from the summit of a mountain.
0
0
Car park gets full up top so park sensibly park close to next car gives more space for others. Don’t park in front of gate as this is used by farmer Go Below and mountain/cave rescue. More parking available at bottom of hill.
0
0
Small train station in the mountains - slate was once mined here - now a tourist attraction.
0
0
Slate was mined here above and below ground from about 1830. The remote location proved difficult, and a series of financial troubles hampered the quarry. It shut during WW1 and reopened afterwards until finally closing in 1948. At it's peak, this was the second-largest underground slate mine in North Wales. Today you can explore the spoil and some of the old machinery.
0
0
No haute cuisine, but coffee and delicious cakes and rustic soups and other dishes. Very good after the strenuous hike.
0
0
There are over 45 dedicated running routes around Tanygrisiau Reservoir, offering a wide range of options for different fitness levels and preferences. The area is highly rated by the komoot community, with an average score of 4.7 stars from over 760 visitors.
Yes, Tanygrisiau Reservoir offers several easy running routes. While the main circular route around the reservoir itself is relatively flat and accessible, you can also find other moderate options. For example, the Coed Tŷ-coch Stream loop from Blaenau Ffestiniog is a moderate 5.6-mile trail that takes about an hour to complete, featuring varied terrain without extreme difficulty.
The terrain around Tanygrisiau Reservoir is quite varied. You'll find relatively flat waterside paths directly bordering the reservoir, but also more rugged sections with ascents into the Moelwyn Mountains. Some trails might involve stream crossings with stepping stones or slightly boggy areas, especially after rain. The landscape seamlessly blends natural beauty with remnants of its industrial past, so you might run on gravel paths, earth trails, and even old quarry tracks.
Absolutely! The region is rich in both natural beauty and industrial heritage. Many trails offer views of waterfalls and pretty streams. For instance, the Cwmorthin Falls – Cwmorthin Slate Mill loop from Blaenau Ffestiniog is a moderate 4.7-mile route where you can encounter both natural cascades and historical slate industry remnants. You might also spot disused quarries and the former Moelwyn Mine along various routes.
Yes, for experienced runners seeking a challenge, the area provides difficult mountain ascents. The Moelwyn Mawr Summit – Moelwyn Bach loop from Blaenau Ffestiniog is a demanding 8.4-mile path with significant elevation gain, offering extensive mountain views and a truly strenuous workout.
Many of the easier, flatter sections around the reservoir are suitable for families, especially those with older children who enjoy walking or light jogging. The scenic waterside trails provide a pleasant environment. However, some routes involve rugged terrain or significant elevation, so it's best to check the difficulty grade of a specific route before heading out with younger family members.
Generally, the trails around Tanygrisiau Reservoir are dog-friendly, but it's always recommended to keep dogs on a lead, especially in areas where livestock may be present or near roads. Be mindful of varying terrain, as some sections might be rocky or involve stream crossings that could be challenging for some dogs. Always carry water for your dog, especially on longer runs.
Beyond the stunning Moelwyn Mountains backdrop, you'll encounter fascinating historical elements. The splendid Ffestiniog Railway runs nearby, and you might catch sight and sound of the heritage steam railway, adding a unique charm. The landscape is also dotted with remnants of the slate-quarrying industry, including disused quarries. The Ffestiniog Power Station itself is an interesting point, showcasing a blend of natural resources and human engineering.
Yes, many of the running routes around Tanygrisiau Reservoir are circular, allowing you to start and finish at the same point without retracing your steps. The popular route directly around the reservoir is a prime example, offering a continuous loop with picturesque views. Most of the routes listed in this guide, such as the Coed Tŷ-coch Stream loop from Llan Ffestiniog, are designed as loops.
Parking is generally available in and around the Tanygrisiau area, often near the Ffestiniog Railway station or designated car parks. Blaenau Ffestiniog, a nearby town, also serves as a common starting point for many routes and offers parking facilities. It's advisable to check specific route descriptions for the most convenient parking options.
Tanygrisiau Reservoir offers a compelling experience year-round. Spring and autumn provide pleasant temperatures and vibrant scenery, with fewer crowds. Summer is popular but can be warmer, while winter offers a dramatic, rugged beauty, though trails might be boggy or icy in places. Always check weather conditions before heading out, as the mountain weather can change rapidly.
Elevation changes vary significantly depending on the route. The circular path directly around Tanygrisiau Reservoir is relatively flat. However, routes venturing into the Moelwyn Mountains, such as the Moelwyn Mawr Summit loop from Blaenau Ffestiniog, involve substantial ascents and descents, with elevation gains exceeding 500 meters. You can find routes with anything from gentle undulations to challenging climbs.


Browse the best Running Trails & Routes in other regions.