A rock and a hard place
North Rona and Sula Sgeir are two very different islands . North Rona is a lush green island , much larger in size than the bare hard rock of Sula Sgeir . However they both play host to seabird colonies .
On the harsh rock of Sula Sgeir some vegetation does grow with seven species of plant able to tolerate the harsh conditions . More than 10,000 pairs of gannets make their home here during the summer , to nest and raise their chicks .
Mayweed that looks like a giant daisy is fuelled by bird poo , and you can find many a young fulmar chick hidden among the flowers . Puffins nest in rock cracks or very shallow burrows among the little vegetated areas , and guillemots and kittiwakes are found round the island , nesting on ledges .
Guillemots lay conical shaped eggs on cliff ledges , with no nest . The shape of the egg stops it rolling off the cliff ledge . The egg is self cleaning . It can repel water as its surface is covered in tiny little cones , making the shell look like the Himalayas through a microscope . When water hits the egg it forms water droplets in perfect spheres , and they fall of when knocked taking all the dirt with it .
North Rona in comparison has 50 species of flowering plant , many species of lichen that profusely grow on the rocks , and 51 species of seaweed compared with just 16 at Sula Sgeir .
It also plays host to one of Britain ’ s rarest seabirds , the Leach ’ s petrel , which breeds in the old ruins . Leach ’ s petrel can live for a long time : one was ringed on North Rona in 1972 and was still nesting there 30 years later .
Nearly a thousand pairs of black-backed gulls nest on the island . Every year in the autumn about a thousand grey seal pups are born on North Rona , and the seal colony has been part of a long-term population study for some time .
Sula Sgeir ’ s main attraction has to be its archway . Probably big enough to fit a small submarine through , this magnificent rock formation stretches from a depth of 10m to the seabed at 35m . Dripping with jewel anemones and dead men ’ s fingers , it is a sight to behold and a privilege to experience .
Our time at Sula Sgeir was to be short-lived . In the evening after our first day there , the weather closed in , forcing us to head for home a day sooner than we had hoped . But what we had seen of these tiny islands will live in our memories for a long time to come . And thanks have to go to our skipper Bob , whose yearning for something different , for something challenging and his previous experience at these sites meant we were constantly placed on exactly the right sites at the right times .
The dramatic underwater scenery , abundant life , clear blue waters and total isolation mean these islands should surely be on every UK diver ’ s bucket list .
RTop : Wave battered rocks on North Rona
far out in the North Atlantic mean only the hardiest species can cling on to survive
RAbove : Crustaceans abound at these
exposed sites , not least the pink shrimp , Pandalus montagui
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