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 (see table below for other definitions).  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.

​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 around 300 km from Hirta (Hiort) 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 around 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. 

On the extended continental shelf 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. Sites can have overlapping designations. 

• 58 Special Areas of Conservation (SACs) for European protected species and habitats. 
• 58 Special Protection Areas (SPAs) for birds.
• 36 Nature Conservation Marine Protected Areas for marine species, habitats, and geological features.
• 16 Ramsar sites for wetlands of international importance.
• 65 Sites of Special Scientific Interest (SSSIs) for species, habitats, and geological features.

These figure does not include other types of MPA such as 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

Illustrative Map	Landward Boundary	Seaward Boundary	Description	Area (km2)
	Mean High Water Spring (MHWS)	Baseline of the Territorial Sea (TS)	Internal Waters (UNCLOS) “Scottish onshore area” in the Scotland Act 1998	34,920
	MHWS	3NM from baseline	Internal Waters + Territorial Sea (part) (UNCLOS) Combined extent of “Transitional” and “Coastal” waters in the Water Environment and Water Services (Scotland) Act 2003	48,710
	MHWS	6NM from baseline	Internal Waters + Territorial Sea (part) (UNCLOS) “Scottish inshore waters” in the Inshore Fishing (Scotland) Act 1984	62,212
	MHWS	Territorial Sea Limit (up to 12NM from baseline)	Internal Waters + Territorial Sea (UNCLOS) “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	90,400
	MHWS	Exclusive Economic Zone Limit (up to 200NM from baseline)	Internal Waters + Territorial Sea + EEZ (UNCLOS) “Scottish Zone” in the Scotland Act 1998	462,315
	MHWS	Continental Shelf Limits (up to 350NM from baseline)	Internal Waters + Territorial Sea + Continental Shelf (UNCLOS) Combined extent of “Scottish inshore region” and “Scottish offshore region” in the Marine and Coastal Access Act 2009	617,643
	Baseline	Territorial Sea Limit	Territorial Sea (UNCLOS)	55,480
	Territorial Sea Limit	Exclusive Economic Zone Limit	Exclusive Economic Zone (UNCLOS)	323,153
	Territorial Sea Limit	Continental Shelf Limits	Continental Shelf (UNCLOS) “Scottish offshore region” in the Marine and Coastal Access Act 2009	527,243

NM = nautical mile

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

* Derived from OS Boundary-Line and subject to the coastline paradox

** 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” under the Marine and Coastal Access Act 2009, but is not defined as a Scottish Marine Region in the The Scottish Marine Regions Order 2015.

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

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