The Gulf Between

The Gulf Between is a natural channel that separates the islands of Fetlar and Unst, two of the northernmost islands in the Shetland archipelago. It runs roughly north-south, connecting the North Sea to the Atlantic Ocean, and is characterized by steep cliffs, rocky shores, and a seabed that drops sharply in places. The strait is narrow, only about 1.5 kilometers wide at its tightest point, and its hydrography is dominated by strong tidal streams that can reach speeds of 4 to 6 knots during spring tides.¹ These currents create standing waves, eddies, and overfalls, making navigation hazardous for small craft. The gulf's waters are also influenced by the surrounding bathymetry, with deep channels and submerged reefs that amplify the turbulence. This combination of narrowness and tidal energy makes the Gulf Between a notable feature in maritime charts, and it is often cited in sailing guides as a challenging passage.²

The Gulf Between has a long maritime history, with records of shipwrecks dating back to the 16th century. The treacherous currents and rocky shores have claimed numerous vessels, including fishing boats and cargo ships, and local lore is replete with tales of narrow escapes and tragic losses. One of the most famous legends associated with the gulf is that of the Stoorworm, a sea serpent said to dwell in its depths, which was believed to capsize boats and devour sailors.³ This myth likely originated from the sight of large seals or whales surfacing in the turbulent waters. In more recent times, the gulf has been used by local fishermen for its rich stocks of whitefish and shellfish, though they must navigate with extreme caution. The area is also a designated marine protected area, reflecting its ecological importance and the need to balance human activity with conservation.⁴

The Gulf Between supports a diverse marine ecosystem, thanks to its strong currents that bring nutrients and oxygen to the water column. The seabed is home to kelp forests, sponges, and coral reefs, which in turn attract a variety of fish species, including cod, saithe, and herring. The cliffs and islands around the gulf are important breeding sites for seabirds such as puffins, guillemots, and razorbills, and the area is recognized as an Important Bird Area by BirdLife International.⁵ The gulf is also a habitat for marine mammals, including harbour seals and otters, which are frequently observed in the calm stretches between tides. Conservation efforts have focused on monitoring water quality and protecting the seabed from bottom trawling, which can damage fragile habitats. The Shetland Islands Council and Scottish Natural Heritage have designated the area as a Special Area of Conservation under the EU Habitats Directive, ensuring its protection for future generations.⁶

Beyond its maritime and ecological significance, the Gulf Between has several lesser-known facets. Geologically, the strait lies along a fault line that has shaped the Shetland landscape, and the exposed rock faces reveal a complex history of volcanic activity and glacial erosion.⁷ In the 19th century, the gulf was a site for kelp harvesting, which was used to produce soda ash for the glass and soap industries. The remains of old kelp kilns can still be seen on the shores of Fetlar. Additionally, the gulf is a popular spot for recreational kayaking, though only experienced paddlers attempt the crossing due to the strong currents. A local tradition holds that throwing a coin into the gulf brings good luck to sailors, a custom that may have pre-Christian origins. The gulf also features in the poetry of Shetland writer Vagaland, who immortalized its moods in his verse.⁸

Stoorworm

A mythical sea serpent in Shetland folklore, said to inhabit the Gulf Between and other waters.

Overfalls

Turbulent water conditions caused by strong currents passing over underwater obstructions.

Kelp kilns

Furnaces used in the 19th century to burn kelp for extracting soda ash.