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

Data Type: 

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. 

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

Landward Boundary Seaward Boundary Description Area (km2)
Mean High Water Spring (MHWS) Baseline of territorial sea (TS)
  • Internal Waters
  • "Scottish Onshore Area"
MHWS 3NM from baseline
  • Internal Waters + Territorial Sea (part)
  • Water Framework Directive Limits
MHWS 6NM from baseline
  • Internal Waters + Territorial Sea (part)
  • "Scottish Inshore Waters"
MHWS Territorial Sea Limit (up to 12NM from baseline)
  • Internal Waters + Territorial Sea | "Scotland"
  • "Scottish inshore region"
  • "Scottish marine area"
MHWS Exclusive Economic Zone Limit (up to 200NM from baseline)
  • Internal Waters + Territorial Sea + EEZ
  • "Scottish Zone"
MHWS Continental Shelf Limits (up to 350NM from baseline)
  • Internal Waters + Territorial Sea + Continental Shelf
  • "Scottish offshore region"
Baseline Territorial Sea Limit
  • Territorial Sea
Territorial Sea Limit Exclusive Economic Zone Limit
  • Exclusive Economic Zone
Territorial Sea Limit Continental Shelf Limits
  • Continental Shelf

NM = nautical mile


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

Scottish Marine Area Area (km2) Distance along MHWS (km)* Deepest Point (m) Shallowest Point (m) Average Depth (m)
Forth and Tay 4,487 775 97 MHWS 39
North East 3,153 307 224 MHWS 63
Moray Firth 5,876 985 256 MHWS 50
Orkney Islands 9,256 1,228 195 MHWS 65
Shetland Isles 12,309 2,382 188 MHWS 93
North Coast 2,443 544 124 MHWS 68
West Highlands 10,420 3,656 322 MHWS 82
Outer Hebrides 20,848 3,915 268 MHWS 88
Argyll 12,044 2,918 320 MHWS 66
Clyde 4,279 1,256 198 MHWS 58
Solway 3,724 777 314 MHWS 52
Offshore Marine Area          
Long Forties 34,508 n/a 178 32 80
Fladen and Moray Firth Offshore 40,261 n/a 248 35 111
East Shetland Shelf 33,713 n/a 175 58 128
North and West Shetland Shelf 28,676 n/a 623 72 254
Faroe Shetland Channel 42,752 n/a 2,418 343 1,304
North Scotland Shelf 28,820 n/a 1,073 15 213
Hebrides Shelf 30,437 n/a 1,359 19 241
Bailey 74,797 n/a 2,360 322 1,365
Hatton 155,215 n/a 3,185 158 1,783
Rockall ** 59,625 # 2,576 MHWS 1,386
Total 617,643 18,743 3,185 MHWS 903
c/f Scottish Zone 462,315 18,743 2,576 MHWS 611

* 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

Description Area (km2) Approx. %
Scottish zone 462,315 63%
English zone 230,190 32%
Welsh zone 30,778 4%
Northern Irish zone 6,819 1%
UK Exclusive Economic Zone (Total) 730,102 100%
Isle of Man territorial waters 3,976  
Guernsey territorial waters 3,691  
Jersey territorial waters 2,965  

Source: UKHO Maritime Limits