Underwater Viewing in The Shetland Sea

Live Underwater Colour Video


Shetland’s wildlife above the surface is spectacular and world-famous (even Alaska doesn’t have such accessible, large seabird cliffs) but beneath the waves it can be even more amazing.

This underwater world used to be Shetland’s best-kept secret, known only to a few hardy scuba divers. But now you don’t have to get cold and wet to see it.

Our 10:15am & 2:15pm boat trips include underwater viewing with a remotely controlled tethered mini-submarine, ‘LOMVI’ (Lowered Overboard Marine Viewing Instrument). A camera on the submarine feeds live colour video images to display screens in the cabin and on deck.

The techniques we’ve pioneered and perfected since 2001 enable us to give you a unique and unforgettable show of the teeming sealife below the surface of The Shetland Sea.

Lights on the underwater camera reveal the astonishing colours and variety of this marine wonderland. It’s not dark and grey down there after all – it’s a Technicolor riot of biodiversity.

Many passengers have told us that these fascinating underwater images are the most memorable and unexpected part of their boat trip with Seabirds-and-Seals. Most surprising of all is the revelation that there’s far more life below the surface of The Shetland Sea than above it.

Early and late in the season the underwater visibility can be astounding here, in one of the most productive seas on Earth.

In summer there’s usually a thick fog of plant plankton with “snowflakes” of animal plankton grazing on it. In a glass-bottomed boat you’d see only a few metres into this “life soup” but with the remotely controlled camera we can steer in close up and see everything in astonishing detail.

Shetland’s secret forest and coral reefs

Diving between 10 and 25 metres down, we discover rocky reefs, boulder-strewn gullies and Shetland’s secret forest – the vast beds of waving kelp fronds that are home to hundreds of species.

We swim the camera inside caves and along submerged cliff faces for extraordinary views of the teeming sealife – including zooplankton, sea urchins, crabs, comb jellies, soft corals, sea anemones, sea mats, and colonies of other strange and ancient animals that look like plants but can survive and thrive in total darkness.

Large fish such as pollack and wrasse cruise by. Sometimes guillemots put on an underwater flying display for us. And we often meet the ever-inquisitive seals – which will occasionally swim up and nuzzle the mini-submarine.

Whatever the weather, you can watch these remarkable underwater images in the comfort of our heated cabin, while enjoying complimentary tea, coffee and biscuits.

Why is The Shetland Sea so rich in plankton?

Satellite picture of green plankton blooms in The Shetland Sea.

The continental shelf around Shetland is one of the richest and most productive seas in the world. As a plankton producer it ranks with the Grand Banks of Newfoundland, Russia’s Sea of Okhotsk and the Gulf of Alaska. Like the deeper waters west of the shelf edge, it is far more “biodiverse” than a casual observer might think.

One reason why there’s so much food for marine plants, animals and birds in The Shetland Sea is the extreme turbulence of our coastal waters.

This is because of:

  • The mingling of Atlantic, Arctic and North Sea currents here on the edge of the Continental Shelf.
  • The churning effect of tide races in the narrow sounds between the islands.
  • Continuous upwelling of bottom water caused by tides and currents running over the drowned cliffs and ridges extending offshore. Some of these submarine obstructions, such as Da Score on the north coast Bressay, rise vertically 40m from the seabed.
  • On top of all that, Shetland endures an average of about 100 days a year when the wind is Force Seven (near-gale) or higher.

Microscopic plant plankton like these are too small to see with the naked eye but keep the whole ecosystem running.

The turbulence caused by all these factors traps large amounts of nutrients (mainly from rotted seaweed and dead plankton) in sunlit water less than 30 metres deep (the “photic zone”). So underwater visibility in Shetland is surprisingly poor between March and September, due to plant plankton “blooms” fed by the profusion of nutrients. The phytoplanktonic “fog”, made up of uncountable trillions of microscopic, single-celled plants, is in turn eaten by swarms of animal plankton. This zooplanktonic “snow”, including the eggs and larvae of all our commercial finfish and shellfish, is food for fish, basking sharks and baleen whales.

The blooms and swarms of plankton extend out to and beyond the continental shelf margin. The plankton may be out of sight and, for most people, out of mind, but it’s the basis of the coastal ecosystem.

Snowflake-sized Copepods like this eat the plant plankton and in turn are food for fish.

The plant plankton also produces a significant proportion of the oxygen we breathe. Without it the oxygen level in the atmosphere would drop below the 21% level at which humans have evolved. This surface layer indeed gave rise to the first plants and still contains most of the world’s flora, by mass. It’s extraordinarily thin and fragile, rarely more than 30 metres deep. In comparison with the diameter of the Earth, the phytoplankton layer is hundreds of times thinner than the skin of a bubble.

At the top of the plankton-based food chain, Shetland seabird breeding colonies like Noss are internationally significant and among the largest in the North Atlantic.