This is a list of P600 mountains in Britain and Ireland by height. A P600 is defined as a mountain with a topographic prominence above 600 m (1,969 ft), regardless of elevation or any other merits (e.g. topographic isolation); this is a similar approach to that of the Marilyn, Simms, HuMP and TuMP British Isle mountain and hill classifications. By definition, P600s have a height above 600 m (1,969 ft), the requirement to be called a "mountain" in the British Isles. The "P" terminology is an international classification,^[1][2] along with P1500 Ultras.^[3][4] P600 and "Majors" are used interchangeably.^[5][6][7]

As of October 2018^[update], there were 120 P600s in the British Isles: 81 in Scotland, 25 in Ireland, 8 in Wales, 4 in England, 1 in Northern Ireland, and 1 in the Isle of Man. The 120 P600s contained 54 of the 282 Scottish Munros, and 10 of the 34 Non-Scottish Munros (or Furths), all of which have heights above 3,000 feet (914.4 m), and are sometimes called the "Super-Majors". The list also contained the highest mountains in Scotland, Wales, Ireland, and England.

On 9 November 2019, Norfolk climber Liam Chase became the first person to complete all 120 P600s in a single calendar year, starting with Cross Fell on 1 January, and ending with Pen y Fan.^[8] Chase was also only the seventh person recorded to have climbed all P600s over any time period.^[8][9]

British Isles mountain cartographer, Alan Dawson, developer of the Marilyns designation,^{[lower-alpha 1][10]} labelled "Majors" as having a prominence of over 2,000 ft (610 m), but no other criteria. Dawson's prominence threshold was the normal height threshold for a British Isles mountain,^[11] and 111 mountains met his definition.^[11] In 2004, Dawson's prominence was converted into a metric threshold of 600 metres (1,969 ft) by Rob Woodall & Jonathan de Ferranti, and labelled the "P600s", a term used by the UIAA for major mountains; the P600s expanded to 119 mountains.^[11][12] The current list has 120 mountains, although there is dispute as to whether Moel Siabod's prominence is above 600 metres (2,000 ft), or is in fact just below the threshold at 599.9 metres.^[12]

This list below was downloaded from the Database of British and Irish Hills ("DoBIH")^{[lower-alpha 2]} in October 2018. Note that topographical prominence, unlike topographical elevation, is far more complex to measure and requires a survey of the entire contours of a peak, rather than a single point of height.^[15] These tables are therefore subject to being revised over time, and should not be amended or updated unless the entire DoBIH data is re-downloaded again.

(‡) Would not have been eligible for Dawson's 2004 "imperial" list of 111 mountains with prominence over 2,000 ft (610 m).
(‡‡) Added since the 2006 "metric" list of 119 mountains with prominence over 2,000 ft (610 m), based on updated surveys.

In 2006, mountain database publisher, Mark Trengove, added a list of seven "Sub–Majors" (to Dawson, Woodall, and de Ferranti's P600 "Majors"), which had a prominence of between 590–600 m (1,940–1,970 ft), and which possibly could become P600s, or Majors, in the future due to any possible discovered "contour uncertainty, rounding error, or map error".^[11][12] Since 2006, one of Trengrove's Sub–Majors, Moel Siabod, was re–surveyed and shown to be a P600 "Major". The list below is the October 2018 DoBIH^{[lower-alpha 2]} list of the six mountains with a prominence between 590–600 m (1,940–1,970 ft) in the British Isles.

The DoBIH uses the following codes for the various classifications of mountains and hills in the British Isles, which many of the above peaks also fall into:^[16][17]

Prefixes

• s sub
• x deleted

Suffixes

• = twin

• List of mountains of the British Isles by height
• Lists of mountains and hills in the British Isles
• List of mountains in Ireland
• List of Munro mountains in Scotland
• List of Murdos (mountains)
• List of Furth mountains in the British Isles
• List of Marilyns in the British Isles