Llyn Mair

Infobox lake
lake_name = Llyn Mair
image_lake = Llyn Mair.jpg
caption_lake = looking towards Coed Llyn Y Garnedd
image_bathymetry =
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location = North Wales
coords = coord|52.95119|N|4.00787|W|region:GB_type:waterbody_source:enwiki-osgb36(SH652412)|display=inline,title
type = artificial lake
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basin_countries = United Kingdom
length =
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area = convert|14|acre|ha|abbr=on
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Llyn Mair "(Welsh : 'Mary's lake')" is a 14 acre artificial lake located at gbm4ibx|SH652412 in North Wales. It lies in the area of Tan-y-Bwlch, a little above Plas Tan-y-Bwlch, and is in the catchment area of the River Dwyryd. It was created by W.E.Oakeley (of Plas Tan-y-bwlch) as a 21st birthday present to his daughter Mair, and as a water supply.

The lake is set alongside the B4410 road, a minor road linking the village of Rhyd. The position of the lake bordered with ancient oak woods and its tranquil appearance makes this a popular picnic site for visitors and it also provides a starting point for a number of local country walks. There is some limited parking available just off the road.

The narrow gauge Ffestiniog Railway runs through the woods above the lake, and Tan-y-Bwlch railway station can be reached on foot from the lake.

The lake also has a notable echo because of the shape of the surrounding hills.