anglesey is a relatively low-lying island, with low hills spaced evenly over the north of 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. at 714 km, it is the 51st largest island in europe, and just five square kilometres smaller than singapore.