Facts and figures about Scotland's sea area (coastline length, sea area in sq kms)

How long is the coastline of Scotland?

We estimate Scotland’s coastline to be 18,743 km in length along the high water line (“mean high water spring” or MHWS)

Coastlines are difficult to measure accurately because of the coastline paradox.  All published figures are estimated, and will vary depending on the size of the ruler used to measure (the scale of the map). 

Source: Ordnance Survey Boundary-Line

How big are Scotland’s seas?

We estimate the area of Scotland’s seas to be 462,315 km² using the definition of the “Scottish zone” in the Scotland Act 1998.  Scotland’s seas are nearly six times larger than the land area of Scotland.

The figure above reflects the UK Exclusive Economic Zone (EEZ) adjacent to Scotland, which accounts for 63% of the UK EEZ.

Other definitions can be used for Scotland’s seas. 

• Internal Waters adjacent to Scotland: 34,920 km²
  
  • High water mark to the baseline of territorial sea
  • “Scottish onshore area” in the Scotland Act 1998

• Territorial Sea adjacent to Scotland: 90,400 km² 
  
  • High water mark to 12NM limit
  • “Scotland” in the Scotland Act 1998
  • “Scottish inshore region” in the Marine and Coastal Access Act 2009
  • “Scottish marine area” in the Marine (Scotland) Act 2010

• Exclusive Economic Zone adjacent to Scotland: 462,315 km²
  
  • High water mark to Exclusive Economic Zone (EEZ) limit
  • “Scottish Zone” in the Scotland Act 1998

• Continental Shelf adjacent to Scotland: 617,643 km²
  
  • High water mark to continental shelf limit
  • Extent of “Scottish inshore region” and “Scottish offshore region” in the Marine and Coastal Access Act 2009

• Scottish inshore waters: 62,212 km²
  
  • High water mark to 6NM limit
  • Extent of “Scottish inshore waters” in the Inshore Fishing (Scotland) Act 1984

• Transitional and coastal waters adjacent to Scotland: 48,710 km²
  
  • High water mark to 3NM limit
  • Extent of “Transitional” and “Coastal” waters in the Water Environment and Water Services (Scotland) Act 2003

The area of sea can vary depending on the map projection and coastline scale used for the calculations. A more detailed coastline can introduce variations and additional islands and skerries.

Sources: UKHO Maritime Limits | SEPA Transitional and Coastal Water Bodies.

How many islands does Scotland have?

We estimate Scotland to have over 900 islands, of which 118 are inhabited.

The most remote Scottish island is Rockall, which is 301 km from Hirta in the St Kilda archipelago.

Source: National Records of Scotland (NRS)

Which part of Scotland is furthest from the sea?

We estimate the furthest point from the sea to be Glen Quoich near Braemar, which is 65 km from the sea.

Source: Ordnance Survey Open Names.

How deep are Scotland’s seas?

The deepest point in the Scottish zone is the Rockall Trough, with a depth of around 2,500m. 

Beyond Rockall, the deepest point in the Scottish offshore region is over 3,000 m deep.  (For comparison, the summit of Ben Nevis is 1,345 m above sea level.)

The average depth of the Scottish zone is around 600 m below sea level, or nearly 1 km (903 m) including the continental shelf limits.

Source: EMODnet 1/16 ArcMinute DEM  

How many Marine Protected Areas are in Scotland? How much of Scottish seas are covered by Marine Protected Areas?

As of March 2022, there are 233 sites for nature conservation covering 228,118 km² or 37% of the continental shelf area adjacent to Scotland. 

This figure does not include other types of Historic MPAs, Demonstration & Research MPAs, or marine management areas such as fisheries-specific restrictions.

Source: JNCC and Scottish Government

How long are Scotland’s rivers and streams?

Scotland has more than 125,000 km of rivers and streams varying from small highland burns to deep, wide lowland rivers such as the Tay.

There is also a 220 km canal network in Scotland.

There are over 25,500 lochs in Scotland, with the Western Isles and Sutherland having the highest concentration of lochs.

Source: SEPA

Table 1: Sea areas of the waters adjacent to Scotland, by United Nations Convention on the Law of the Sea definitions

NM = nautical mile

Table 2: Sea area, coastlines and depths of the Scottish Marine Regions and Offshore Marine Regions (to Continental Shelf Limits)

* Includes small skerries and islets

** The Rockall assessment area also includes the inshore area within the territorial sea. The territorial sea around Rockall is part of the Scottish inshore region, but is not defined as a Scottish Marine Region.

# The coastline of Rockall is not mapped at a suitable scale

The area figures for regions (SMRs and OMRs) and depths presented here are different from those presented in Scotland’s Marine Atlas (2011) for a few reasons:

• Scottish Marine Regions were only created in 2013 and do not correspond to any of the Scottish Sea Areas used in 2011.
• Offshore Marine Regions were subsequently adopted for Scotland’s Marine Assessment 2020 by adjusting the residual 2011 Atlas Scottish Seas Areas by removing the newly established SMR areas.
• In 2013, the UK formally adopted an EEZ, by The Exclusive Economic Zone Order 2013, which adjusted the outer boundary of the Scottish zone.
• Depths (average and maximum) have changed due to the availability of higher resolution depth data and noting the lack of comparability of the old and new regions.

Sources: OceanWise 1 ArcSecond DEM | EMODnet 1/16 ArcMinute DEM  | Ordnance Survey Boundary-Line | UKHO Maritime Limits

Table 3: Sea areas of UK Countries and Crown Dependencies

Source: UKHO Maritime Limits