Y Llethr

{{Short description|Mountain in Snowdonia, Wales}}

{{Use dmy dates|date=August 2019}}

{{Infobox mountain

| name = Y Llethr

| photo = Y Llethr across Llyn Hywel from scree slope of Rhinog Fach - geograph.org.uk - 534766.jpg

| photo_caption = Y Llethr from above Llyn Hywel

| elevation_m = 756

| elevation_ref =

| prominence_m = 561

| prominence_ref =

| parent_peak = Moel Siabod

| listing = Marilyn, Hewitt, Nuttall

| translation = the slope

| language = Welsh

| pronunciation = {{IPA|cy|ə ˈɬɛθr|lang}}

| location = Gwynedd, Wales

| range = Rhinogydd

| coordinates = {{coord|52|48|46.8|N|3|59|9.6|W|display=inline,title|region:GB_type:landmark}}

| grid_ref_UK = SH661258

| topo = OS Landranger 124

| easiest_route =

}}

{{GB summits start}}

{{GB summits entry|Name=Diffwys|Height={{convert|750|m|ft|0}}|Gridref=|Status=sub Marilyn, Hewitt, Nuttall}}

{{GB summits entry|Name=Rhinog Fach|Height={{convert|712|m|ft|0}}|Gridref=|Status=sub Marilyn, Hewitt, Nuttall}}

{{GB summits entry|Name=Crib-y-rhiw|Height={{convert|670|m|ft|0}}|Gridref=|Status= Nuttall}}

{{end}}

Y Llethr is the highest mountain in the Rhinogydd range of Snowdonia, in north Wales. The summit consists of a flat grassy top marked only by a small cairn. The summit is more in keeping with its southern flanks than its rugged northern approach.

The shortest route to the summit goes from the valley of Cwm Nantcol in the west, either directly or via Bwlch Drws Ardudwy and over the mountain of Rhinog Fach. To the south lies the mountain of Diffwys, to the south-east lies the mountain of Y Garn, to the north lies Rhinog Fach and to the west lies the hill of Moelfre.Marsh, Terry. The Summits of Snowdonia, (London: Robert Hale, 1984).Marsh, Terry. The Mountains of Wales, (London: Hodder and Stoughton, 1985).Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition ed.). Milnthorpe, Cumbria: Cicerone. {{ISBN|1-85284-304-7}}.