There are 2,009 Marilyns identified: 1,217 in Scotland, 453 in Ireland (of which 65 are in Northern Ireland), 176 in England, 158 in Wales, 5 on the Isle of Man. Black Mountain, in the Black Mountains, on the border between England and Wales, was formerly counted in both countries but is now treated as being in Wales only. The list of Marilyns in Britain was compiled by Alan Dawson in his book The Relative Hills of Britain, and continues to change as newer surveys revise height measurements for hills and the cols between them. The list was extended into Ireland by Clem Clements in a booklet, The Hewitts and Marilyns of Ireland.
Nearly 80% of Marilyns in Great Britain are in Scotland. They logically extend earlier Scottish lists such as the Munros, Corbetts, Grahams and Donalds. All Corbetts and Grahams, 203 of the 282 Munros, and around half of the Donalds are also Marilyns.
Some hillwalkers attempt to climb as many Marilyns as possible (a pastime known as peak bagging). Some amateur radio operators attempt to operate from the summit of every Marilyn. On 13 October 2014 Rob Woodall became the first person to climb all the Marilyns in Great Britain, including the sea stacks on St Kilda, part of the largest gannet nesting site in the world, maintained by the National Trust for Scotland. Eddie Dealtry became the second person to achieve Woodall's feat, later on the same day.