Llyn-y-Cau, Cader Idris is 1774 landscape painting by the Welsh artist Richard Wilson. It portrays the lake of Llyn-y-Cau near the summit Cadair Idris (Cader Idris) in Snowdonia in North Wales. Wilson, a Welsh painter spent much of his career in London and Italy, but also produced landscape of his native country. It is likely to be a painting he submitted to the Royal Academy's Summer Exhibition of 1774 in Pall Mall. Today the painting is in the collection of the Tate Britain in Pimlico, having been acquired in 1945.