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Visiting Snowdonia

Cader Idris from Foel Caerynwch


Dyffryn Maentwrog and Llyn Mair footpaths

The Dyffryn Maentwrog & Llyn Mair footpath network is extensive and includes over 30km of paths. The network was established for your enjoyment in 1989 by a partnership of local landowners and the numbered posts at path junctions will help you to find exactly where you are on the map.

NOTICE: The permissive paths on the Llyn Mair and Dyffryn Maentwrog footpath network will be closed annually on the 28th of February and can close at any other time without notice.

Distance: Footpath network of over 30km in total
Location: Plas Tan y Bwlch and other various parking locations (see map for further details)
Relevant map: Ordnance Survey OL 18 Harlech, Porthmadog and Bala
Useful Information: Wear comfortable walking shoes

Dyffryn Maentwrog and Llyn Mair footpaths map

Click on the map to view a larger pdf version


Much of the romance of exploring these paths is discovering, among the rich variety of wildlife and habitats, those tell-tale signs which show the area's rich historical heritage.

Look for:

old estate paths some dating back to the 18C when the Maentwrog valley was landscaped by the Plas Tan y Bwlch estate.

the river Dwyryd, visible from several viewpoints, originally ran through a network of saltmarsh channels on the floor of the impressive glaciated Maentwrog valley. The land was claimed for agriculture in 1797 and the river henceforth confined between dykes which snake their way from one side of the valley to the other.

forestry roads and tracks, old and new. Oak was commercially grown here in the 18-19C primarily for the ship-building industry at Porthmadog from where slates were exported all over the world. Some conifers were also grown for the quarries at Blaenau Ffestiniog, which were the main source of income to the Oakeley family of Plas Tan y Bwlch. The present conifer plantation dates from the 1960s.

the Ffestiniog Railway - from 1836 carried slates from Blaenau Ffestiniog to Porthmadog. Today its' trains, mostly steam hauled, carry tourists, and also provide a link at Penrhyn, Plas Halt and Tan y Bwlch stations for walks in the footpath network.

the old road through Rhyd - part of which was a Roman road (Sarn Helen); drove road and one of the main coach roads through the area.

remains of stone walls and buildings related to agriculture, forestry, gamekeeping and, in the area of Penrallt, old lead mines.

lakes - Llyn Mair was built in 1889, and Llyn Hafod y Llyn is from the same period. The Millpond in the gorge below Llyn Mair once supplied water to power the estate saw mill, flour mill and a turbine which generated electricity for the Plas and village of Maentwrog. Llyn Trefor to the west was a drinking water reservoir supplying houses down slope.


The Maentwrog oak woodlands are managed as reserves by a number of organisations because of their wealth of wildlife. In addition the woodlands in the valley are recognised as being of European importance by being designated as a Special Area of Conservation (SAC), because of the large extent of upland oak woodland. This special habitat provides ideal conditions for mosses, liverworts and lichens and the rare bats that are found in the area. Notably the lesser horseshoe bat has its European stronghold here.

Birds - spring and summer are extremely good in the oak woodlands for pied flycatchers, redstarts and wood warblers as well as excellent numbers of our more familiar birds, while Llyn Mair over the winter is a magnet for wild ducks. Other birds recorded here are nightjar, goshawk and osprey.

Animals - fox and badger signs are plentiful, but remember that nine species of bats and the elusive pine marten have also been recorded here.

Plants - the most important element is the fantastic diversity of mosses, lichens and ferns growing on the oaks. Hundreds of different species are found here and their wonderful combinations of colours and forms are truly amazing.

Dyffryn Maentwrog

Dyffryn Maentwrog (© SNPA)

Header image - Morfa Harlech (© Crown copyright (2014) Visit Wales)