According to surviving folklore, Orkney was once home to two distinct types of trow.

The first, and by far the most familiar, were the mischievous, and frequently malevolent, hill-trows, who dwelled in the islands' many hollow hills and mounds.

The second are known simply as sea-trows.

These creatures dwelled in the waters around the islands. Tradition has it that, at some time in the distant past, they shared the land with the hill-trows. For some, now forgotten, reason they were banished to the sea. In Orkney, details of this feud, and the enforced exile that followed, have been lost.

The sea-trow was also said to be the ugliest creature imaginable.

Described as having a face like that of a monkey, with huge unwieldy limbs, the sea-trow’s head  sloped to a sharp angle at top. Its body was wizened and its feet flat, round as millstones and, like his fingers, webbed. With skin that was scaly, and lank, matted hair like seaweed falling round his head, Orcadian storytellers often referred to the sea-trow as “Tangy” – from the dialect word “tang” meaning “seaweed”.

Like the other supernatural denizens of the sea, the sea-trows were fond of returning to the land, but out of water their grotesque shape meant their movements were clumsy, slow and waddling.

Their favourite onshore haunt was the "foreshore", the area of ground between high and low water. Although the poor sea-trow would have dearly loved to extend his onshore wanderings inland, he could not do so safely for fear of his deadly enemies, the hill-trows. The sea was the only place the sea-trow was safe from its land-dwelling cousins.

Unlike the archetypal trow, the sea-trows were notoriously stupid.

Although they were not represented as evil creatures, they often played tricks on the few humans they encountered. More often than not, however, the sea-trow's stupidity meant that their pranks backfired, leaving the bewildered creature in a state of utter confusion.

As well as being stupid, the sea-trow was notoriously lazy.

Rather than catch fish for himself, the sea-trow preferred to lie on the seabed watching the mortal fishermen's lines above. When a fish was hooked, the sea-trow would unhook it quickly and devour it greedily. Many a poor fisherman went home empty-handed because of thieving sea-trows.

Where the fishing was poor, and the fish weren't biting, the sea-trow satisfied his hunger by removing the bait from the fishermen’s hook. This was a dangerous prank, for the sea-trow himself was sometimes hooked and drawn up to the surface where, if his frightful appearance did not terrify the fishermen, he was punished for his insolence.

One such story is told in an old Orcadian rhyme.

After describing the dread terror of the boatmen at seeing the misshapen monster alongside the boat after hauling him up on one of their lines, the rhyme says:

"The Geudman o' Ancum was grippid wi grace,
He ap wi the aethic steen, an sank i his face,
An heem day rowed i muckel fare,
An sang a psalm, an meed a prayer."

And that is all the surviving lore on the Orkney sea-trow.

Although tradition abounds with tales of the hill-trows, and their exploits, information on their aquatic cousins is much rarer. In the tale of the Copinsay Brownie, we get a tantalising glimpse of a creature that seems to be related somehow, but there is very little else.

"They tell us that several such Creatures do appear to Fishers at Sea, particularly such as they call Sea-Trowes, great rolling Creatures, tumbling in the waters, which, if they come among their nets they break them, and sometimes takes them away with them;

If the Fishers see them before they come near, they endeavour to keep them off with their oars or long staves, and if they can get them beaten therewith, they will endeavour to do it:

The Fishers both in Orkney and Zetland are affraid when they see them, which panick fear of their's makes them think and sometimes say that it is the Devil in the shape of such Creatures, whether it be so or not as they apprehend, I cannot determine. However, it seems to be more than probable, that evil spirits frequent both Sea and Land."

Rev John Brand; 1703

Comparing the earliest reports of the folklore with the surviving accounts, I believe the sea-trow is a development of an earlier term.

As I discuss elsewhere, the term "trow" was once used throughout Orkney to refer to any spirit or monster. In the same way "sea-trow" probably applied to a collection of unnatural "sea spirits".

Turning to the 16th century writings of Jo Ben, for example, we can read of one of the sea dwelling "trowis" - a monster that was: "clad in seaweed, in its whole body it is like a foal, with curly hair, it has a member like that of a horse and large testicles."

Slightly different to our slow-witted, ape-like sea-trow account that survives today.

I believe that when a variant of one, or more, of these tales came to be recorded by Walter Traill Dennison in the 19th century, his “version” of the neatly labelled “sea-trow” soon became the norm.

But there is another element that needs to be looked at.

Behind all the tales of the trow tales of folklore lies the creature known in Scandinavian myth as the draugr. This connection applies to the sea-trow too.

For example, Orkney folklore dictates that the sea-trows and the hill-trows were mortal enemies, after the hill-trows had banished the sea-trows to the sea. Whenever the two met fearful battles would result.

This enmity between the two puzzled me for a long time - until I encountered a Norwegian folk tale relating to the sea-dwelling draug and it’s continual battles with the dead on land.

In Norway, the draug was a solitary creature, circling the boats of the unwary, sometimes invisible. Although known to be responsible for a few drownings after capsizing boats, the draug was generally harmless. Its appearance, however, was said to be a certain omen of death.

The draug was often identified with drowned seamen – men who had been denied a burial and therefore doomed to haunt the sea and the coastlines. As such, the draug had human form but with a head made of seaweed. This parallels the Orkney tradition that the creature’s lank, matted hair looked like seaweed.

These draug tales inevitably survived in Orkney. By the time Traill Dennison came to record what survived of these stories, he introduced the term “sea-trow” as a convenient means of distinguishing the lore from that of the land trows.