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The Oceans Surrounding Mainland, Orkney, Scotland


A photograph of Waulkmill Bay, Mainland, Orkney Islands. This beach is located on the southern shore of Mainland. Credit to orkney.com.
A photograph of Waulkmill Bay, Mainland, Orkney Islands. This beach is located on the southern shore of Mainland. Credit to orkney.com.

Today’s article shall discuss the oceans surrounding Mainland, Scotland, an island in the Orkneys.


Mainland is an island located in the Orkney Islands Archipelago approximately 6 miles off the coast of Scotland. It is the largest island in the Orkney Archipelago, & the tenth largest island in the British Isles, at approximately 202 square miles. It holds the bulk of Orkney's population in its main settlement, Kirkwall, with a population of 10,020.


Known for its vast biodiversity of both terrestrial & marine life, peaceful coastal communities, & rolling green hills, Mainland is a picturesque island.


The island is home to a variety of unique marine fauna such as puffins, anemones, sea stars, hermit crabs, common seals, grey seals, Eurasian otters, minke whales, & sperm whales. The coastline is positively teeming with marine life, & the rolling waves are filled with creatures galore.


In today’s article, we are going to delve into the salinity, tides, temperatures, marine geography, marine ecosystems, marine flora, & marine fauna of Mainland, Scotland. With that being said, let us plunge into the fascinating seas surrounding Mainland!


The Salinity, Tides, Temperatures, Depth, & Marine Geography of Mainland

Mainland is situated in the North Atlantic Ocean off the coast of Scotland. The salinity around the isle is estimated to be between 35.5 & 36 parts per thousand. Salinity is measured in 1000-gram increments of water, & for every 1000 grams of water, a certain amount of salt is present. This measurement is called parts per thousand, or practical salinity units. This is how salinity or saline level is measured.


There are a variety of websites which provide tidal charts for the Orkney Islands, including

https://easytide.admiralty.co.uk/?PortID=0273. The tide usually ranges from 10.66 to 0.66 feet (3.25 to 0.2 meters).


Similarly, there are a plethora of websites which provide sea surface temperature charts for the Orkney Islands, such as https://seatemperature.info/orkney-water-temperature.html, & https://www.seatemperature.org/europe/united-kingdom/orkney.htm. The approximate annual average water temperature is 50.41° Fahrenheit (10.22° Celsius). According to this average, it is recommended that anyone who desires to engage in diving, or a similar aquatic recreation should use a 7 millimeter thick wet suit, or a semi-dry suit.


Mainland is surrounded by moderately deep water, ranging from 4.9 to 315 feet (1.49 to 96 meters) deep to the north. There are no sea mounts in the nearby area, with the seafloor primarily being composed of rock, gravel, shells, sand, & pebbles of varying sizes.


The Marine Ecosystems of Mainland


Ecosystem Type No. 1: Intertidal Zones

An intertidal zone is an area of coastline that is exposed to air at low tide, & is covered with water at high tide. It is a very important location to many small marine animals, such as gastropods, crustaceans, & bivalves. Many animals will take advantage of the nutrients & microorganisms that come in with the high tide. Tide pools are a kind of rock formation located in the intertidal zone, in which water becomes trapped to form a small pool. These pools generally have species from the phyla Echinodermata & Mollusca in them. Around Mainland, these tidepools are positively teeming with all sorts of marine critters, such as limpets, sea stars, & hermit crabs.


A photograph of the extraordinary tidepools on Mainland at Warebeth Beach. Credit to Catriona Crawford.
A photograph of the extraordinary tidepools on Mainland at Warebeth Beach. Credit to Catriona Crawford.

Ecosystem Type No. 2: Kelp Forests

Kelp forests are some of the largest marine ecosystems around Scotland. Kelp forests are large areas of kelp, that stretch for miles & miles. Each kelp stalk ranges from 25 to 100 feet (7.62 meters to 30.48 meters) tall. There are numerous different species, with the most common being oarweed, sugar kelp, & dabberlock. Similar to trees, kelp absorbs carbon, often at a much faster rate. Without these kelp forests, mitigating the effects of carbon dioxide emissions would be a much bleaker task. These kelp forests are usually found in areas no shallower than 27 feet (8.2296 meters), & areas no deeper than 179 feet (54.5592 meters). They are extraordinarily biodiverse, & support every size & shape of marine life, such as beadlet anemones, cod, pollock, haddock, diving birds, seals, as well as various crustaceans.


They are also important in reducing coastal damage caused by storms, with kelp forests absorbing the brunt of wave energy.


A photograph of a mix of oarweed (Laminaria digitata), & cuvie (Laminaria hyperborea) growing along the shoreline at low tide in Scotland. Credit to the Scottish Seabird Center.
A photograph of a mix of oarweed (Laminaria digitata), & cuvie (Laminaria hyperborea) growing along the shoreline at low tide in Scotland. Credit to the Scottish Seabird Center.

The Marine Flora of Mainland

The Orkneys are rich in marine flora & fauna alike. Oarweed, dabberlocks, & sugar kelp litter the shores, creating quite the spectacle during low tide. Below, we provide an overview of each to give you a bit of oceanic knowledge to hold in your back pocket the next time you visit the Scottish coast. It is important to note that while kelp is photosynthetic, it is technically not a plant, it is a type of protist known as a stramenopile.


Oarweed (Laminaria digitata)

Oarweed is a kind of large brown algae native to the North Atlantic. They are commonly found in shallow waters up to 65.6 feet (20 meters) deep. They are characterized by their long brown rectangular fronds, which split off from a central stipe, akin to fingers branching out from the palm of a hand. It is well known for its numerous health benefits, as well as its culinary & cosmetic applications.


A photograph of oarweed (Laminaria digitata), in clear cool coastal waters growing off the coast of Norway. Credit to reeflings.com.
A photograph of oarweed (Laminaria digitata), in clear cool coastal waters growing off the coast of Norway. Credit to reeflings.com.

Dabberlocks (Alaria esculenta)

Dabberlocks, also known as badderlocks, is a kind of seaweed native to the North Atlantic. They are frequently found in shallow waters up to 114.8 feet (35 meters) deep. They are characterized by their brownish olive-green colour, with 3.28 to 4.9 feet (1 to 1.5 meters) long feathery fronds.


A photograph of Dabberlocks (Alaria esculenta), growing in the Isles of Sicily. Credit to R. Mitchell.
A photograph of Dabberlocks (Alaria esculenta), growing in the Isles of Sicily. Credit to R. Mitchell.

Sugar Kelp (Saccharina latissima)

Sugar Kelp, also colloquially referred to as the Devil’s Belt is a species of seaweed native to the Mid & North Atlantic. It is frequently found growing in coastal environments in waters up to 98 feet (30 meters) deep. They are characterized by long crinkled belt-like fronds up to 16.4 feet (5 meters) in length. They are well known for their culinary applications, particularly in Japanese & Korean Cuisine.


An abundance of sugar kelp (Saccharina latissima) growing in shallow waters off the coast. Credit to seaveg.com.
An abundance of sugar kelp (Saccharina latissima) growing in shallow waters off the coast. Credit to seaveg.com.

The Marine Fauna of Mainland

Mainland is extremely biodiverse, both on land & in the sea. Cetaceans, crustaceans, pinnipeds, diving seabirds, cnidarians, & protists are all commonly seen. Some of the most common creatures include anemones, sea stars, hermit crabs, common seals, grey seals, Eurasian otters, dolphins, porpoises, minke whales, pilot whales, sperm whales, humpback whales, & orcas.


A female Eurasian Sea Otter devouring a wrasse in a bed of kelp on the coast. Credit to the North Isles Landscape Partnership Scheme.
A female Eurasian Sea Otter devouring a wrasse in a bed of kelp on the coast. Credit to the North Isles Landscape Partnership Scheme.

Directories / Credits


Citation 1: “Beaches”, Written by Unknown, & Published at an Unknown Date. Published by Orkney.com.


Citation 2: “NorthLink Ferries”, Written by Charles Tait, & Published at an Unknown Date. Published by NorthLink Ferries.


Citation 3: “Sea Life”, Written by Unknown, & Published at an Unknown Date. Published by Orkney.com.


Citation 4: “Orkney Wildlife”, Written by Cory Jones, & Published on April 20th, 2018. Published by Wilderness Scotland.


Citation 5: “Unique wildlife in Orkney & where to find it”, Written by Magnus Dixon, & Published on an Unknown date. Published by North Link Ferries.


Citation 6: “Orkney Isles & Pentland First Imma”, Written by Unknown & Published at an Unknown date. Published by the Marine Mammal Protected Areas Task Force.


Citation 7: “Orkney Tide Times”, Written by Unknown, & Published at an Unknown Date. Published by TideTime.


Citation 8: “Orkney Tide Times For Today”, Written by Unknown, & Published at an Unknown Date. Published by Tideschart.


Citation 9: “KIRKWALL, Scotland”, Written by Unknown, & Published at an Unknown Date. Published by the UK Hydrographic Office.


Citation 10: “Water temperature in Orkney”, Written by Unknown, & Published at an Unknown Date. Published by Sea Temperature Info.


Citation 11: “Orkney Sea Temperature”, Written by Unknown, & Published at an Unknown Date. Published by seatemperature.org.


Citation No. 12: “Wetsuit thickness & temperature guide”, Written by Mark Evans, & Published on April 24th, 2023, at 3:05 PM. Published By Scuba Divers Magazine.


Citation No. 13: “Kelp forests could cut force of Scotland's storm waves by 70%“, Written by Rob Hutchins, & Published on December 8th, 2025. Published by Oceanographic Magazine.


Citation 14: “Oarweed”, Written by Unknown, & Published at an Unknown Date. Published by Wildlife Trusts.


Citation 15: “Dabberlocks”, Written by Unknown & Published at an Unknown Date. Published by The Marine Life Information Network.


Citation 16: “Sugar Kelp”, Written by Unknown & Published at an Unknown Date. Published by Wildlife Trusts.


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