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Marchlyn Bach Reservoir – Llanberis Tunnel loop from Llanberis

Routes

Bike touring routes & trails

Marchlyn Bach Reservoir – Llanberis Tunnel loop from Llanberis

Hard

5.0

(1)

riders

Marchlyn Bach Reservoir – Llanberis Tunnel loop from Llanberis

01:58

25.3km

660m

Cycling

Hard bike ride. Very good fitness required. Mostly paved surfaces. Suitable for all skill levels. The starting point of the route is accessible with public transport.

Last updated: May 27, 2026

Tips

Your route passes through protected areas

Please check local regulations for:

Parc Cenedlaethol Eryri

Eryri SSSI

Waypoints

Start point

Bus stop

Get Directions

830 m

Llyn Padarn

Highlight • Natural

Llyn Padarn is a glacial lake that's about 3.2km long. The lake side trail makes a great flat run which is a nice change from running around the mountains of …

Tip by

2.77 km

View of Llyn Padarn from Pont Pen-y-Llyn

Highlight • Viewpoint

On a clear day, from this end of Llyn Padarn you’ll get an enticing view of Snowdon and other peaks.
Its absolutely stunning and well worth the ride.

Tip by

4.67 km

Marchlyn Mawr reservoir is a high level lake in Snowdonia behind Elidir Fawr mountain. It is used as the high level water source for Dinorwig electric power station, a closed-loop pumped storage hydroelectric generating facility.

Tip by

12.9 km

Marchlyn Bach Reservoir

Highlight • Lake

Marchlyn Bach Reservoir
The Marchlyn Bach dam and reservoir is not part of the Dinorwig HEP scheme. It is a reservoir owned by Dwr Cymru (Welsh Water).
The road in …

Tip by

23.3 km

Llanberis Tunnel

Highlight • Structure

Great bike path with a small section through the hill for a change!

Tip by

25.3 km

End point

Bus stop

Way Types & Surfaces

Way Types

19.8 km

3.84 km

1.12 km

296 m

271 m

Surfaces

16.2 km

8.87 km

191 m

Elevation

Nothing selected – click and drag below to see the stats for a specific part of the route.

Highest point (630 m)

Lowest point (100 m)

Weather

Thursday 9 July

28°C

12°C

-- %

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Comments

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Our route recommendations are based on thousands of hikes, rides, and runs completed by other people on komoot.

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Marchlyn Bach Reservoir – Llanberis Tunnel loop from Llanberis

Llyn Padarn

View of Llyn Padarn from Pont Pen-y-Llyn

Steep Descent

Marchlyn Mawr Reservoir

Marchlyn Bach Reservoir

Llanberis Tunnel

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