Tal-y-llyn Lake, also known as Talyllyn Lake or Llyn Mwyngil, is a large glacial ribbon lake

Ribbon lake

A ribbon lake or loch is a long and narrow, finger-shaped lake, usually found in a glacial trough. Its formation begins when a glacier moves over an area containing alternate bands of hard and soft bedrock...

 formed by a post-glacial massive landslip damming up the lake within the glaciated valley. It is situated at the foot of Cadair Idris

Cadair Idris

Cadair Idris or Cader Idris is a mountain in Gwynedd, Wales that lies at the southern end of the Snowdonia National Park. The peak, which is one of the most popular in Wales for walkers and hikers,  is composed largely of Ordovician igneous rocks, with classic glacial erosion features such as...

, in the Snowdonia

Snowdonia

Snowdonia is a region in north Wales and a national park of in area. It was the first to be designated of the three National Parks in Wales, in 1951.-Name and extent:...

 mountain range of Gwynedd

Gwynedd

Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...

, Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

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The River Dysynni

River Dysynni

The River Dysynni is a river in mid Wales.- Source :The River Dysynni flows from the western end of Tal-y-llyn Lake and enters Cardigan Bay through the Broad Water lagoon to the north of Tywyn near Tonfanau.-External links:**...

 flows from the lake, through the village of Abergynolwyn

Abergynolwyn

Abergynolwyn is a village in southern Gwynedd, Wales, located at the confluence of the Nant Gwernol and the Afon Dysynni.Historically, the village was part of Merionethshire and its main industry was slate quarrying and the village was founded in the 1860s to house workers at the nearby Bryn...

, and discharges into the sea north of Tywyn

Tywyn

Tywyn is a town and seaside resort on the Cardigan Bay coast of southern Gwynedd , in north Wales. The name derives from the Welsh tywyn and the town is sometimes referred to as Tywyn Meirionnydd...

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The narrow gauge Talyllyn Railway

Talyllyn Railway

The Talyllyn Railway is a narrow-gauge preserved railway in Wales running for from Tywyn on the Mid-Wales coast to Nant Gwernol near the village of Abergynolwyn. The line was opened in 1866 to carry slate from the quarries at Bryn Eglwys to Tywyn, and was the first narrow gauge railway in Britain...

 has its eastern terminus at nearby Abergynolwyn, within the parish of Talyllyn

Talyllyn

Talyllyn or Tal-y-llyn can refer to:* the former parish in southern Merionethshire in Wales, and included the villages of Abergynolwyn and Corris*Tal-y-llyn Lake, a glacial ribbon lake east of Abergynolwyn...

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In 2009 a landscape photograph of the lake was included as an official desktop wallpaper (GB-wp3) with the release of the Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 Windows 7, thus bring an image of the lake to millions of desktop PCs.

In fiction

1976 Newbury Medal winner Susan Cooper

Susan Cooper

Susan Mary Cooper is an English author best known for The Dark Is Rising, an award-winning five-volume saga set in and around England and Wales. The books incorporate traditional British mythology, such as Arthurian and other Welsh elements with original material ; these books were adapted into a...

 used the lake as a setting for the book The Grey King

The Grey King

The Grey King is a children's fantasy novel by British author Susan Cooper, which was awarded the Newbery Medal for excellence in U.S. children's literature in 1976. It is the fourth of five stories in her young adult Arthurian fantasy cycle, The Dark Is Rising...

. Within the lake six sleepers lie, wakened by Will Stanton playing the Harp of Gold. Afterward, they ride to aid the of the Light in the book Silver on the Tree.