Anglesey the island. The highest six are Holyhead Mountain, ; Mynydd Bodafon, ; Mynydd Llaneilian, ; Mynydd y Garn, ; Bwrdd Arthur, ; and Mynydd Llwydiarth, . To the south and south-east the island is separated from the Welsh mainland by the Menai Strait, which at its narrowest point is about wide. In all other directions the island is surrounded by the Irish Sea. It is the 51st largest island in Europe, and just five square kilometres smaller than Singapore. There are several small towns scattered around the island, making it quite evenly populated. The largest are Holyhead, Llangefni, Benllech, Menai
Anglesey at Mona is a nesting site for skylarks. The sheer cliff faces at South Stack near Holyhead provide nesting sites for huge numbers of auks including puffins, razorbills and guillemots together with choughs and peregrine falcons. Three sites on Anglesey are important for breeding terns – see Anglesey tern colonies. There are significant occurrences of the "Juncus subnodulosus"-"Cirsium palustre" fen-meadow plant association, a habitat characterised by certain hydrophilic grasses, sedges and forbs. Anglesey is home to several species of tern, including the roseate tern. Anglesey is home to two of the UK's few remaining colonies of red squirrels, at Pentraeth