Islands at the edge of the world: exploring St Kilda’s sea caves

The World Heritage Site, St Kilda, lies 41 miles west of Benbecula in the Outer Hebrides and is the most remote part of the British Isles. With life on the islands becoming increasingly challenging, the archipelago’s last 36 human residents were evacuated to the mainland in 1930.

However, the islands remain hugely important for their wildlife: they host huge seabird populations, including the world’s second largest colony of North Atlantic gannets; and the waters around St Kilda are designated a Special Area of Conservation (SAC) for their reefs and sea caves, which attract a wealth of spectacular  sea life.  Lisa Kamphausen, from our marine team, has recently returned from these ‘islands at the edge of the world’.


When you get the once-in-a-lifetime opportunity to join a survey to study the sea caves at St Kilda and North Rona, make sure you can make it. It’s an experience you are unlikely to forget.

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That said though, coming face to face with a large seal, 100m into a passageway etched into the side of a rock miles and miles from anywhere in the Atlantic Ocean, it did cross my mind that knitting might be something I’d like to take up when I got home. If I got home.

Madadh Beag

Two weeks of storms, engine failures and sheer bad luck had thwarted all of our previous attempts to make it out to the islands. So our boat was buzzing with excitement when the islands finally appeared in view and we all realised we would get a chance to jump into the blue oceanic waters to join the sea cave dwellers in their dark tunnels for a few hours.

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It was very clear that people are only granted fleeting visits to the world of sea caves: fleeting visits, however, which we certainly made the most of. Between line-laying and measuring, defining biological zones, taking video and photographs, recording the details of animals which live inside the caves, and collecting specimens for the Natural History Museum, we had quite a few jobs to do between us. But we could only stay as long as our Scuba tanks would give us air, our dry suits would keep us warm, our torches had batteries, and as long as the wind blew from the right direction to avoid the worst of the swell.

Dun Arch Transect

In a mad flurry of dawn to dusk activity and against all odds, the team conducting this Site Condition Monitoring survey of the St Kilda SAC was able to survey five sea caves on St Kilda and three on North Rona. And I’m happy to know that there are plenty more caves left to explore which we did not manage to enter during this survey.

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When you get the once-in-a-lifetime opportunity to set up a survey to study sea caves in St Kilda and North Rona, make sure you remember to take a professional photographer along, it will be worth it.

Our website has more info on World Heritage Sites, Site Condition Monitoring and the St Kilda National Nature Reserve. We’ve uploaded hundreds of photos from past marine surveys to FlickR for you to browse and share – all we ask is that your credit Scottish Natural Heritage.

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