At the north end of the island of Bryher, past the heathered turf and Neolithic burial cairns of Shipman Head Down, and the infamous tumult of Hell Bay, is Shipman Head: a bird reserve and, at high tide, a separate island. The tide now, however, is as low as it gets. Following a social media tip, we dump our rucksacks and climb down a cliff of bulging granite to find the narrowest of dividing waters: a sea-hewn zawn, three or four metres wide, 20 metres long, and so straight it might have been deliberately cut.
The petrol-blue water is calm and inviting, if rather a long way down. I peel off to my swimsuit and make a cautious barefoot descent– there’s no shortage of holds and the wave-worn barnacles provide grip without lacerating. The walls are studded with limpets and beadlet anemones, giving an indication of the water level at high tide, when this chasm must be ferocious. I teeter on a ledge and, from above, the kids count down, goading me into a dive.
The water is chilly – it always is on Bryher – but not shockingly so. After a couple of slow lengths, there’s an abrupt splash near the huge rock that chocks the Hell Bay end and makes the channel swimmable. I think I catch movement in the far periphery of my vision, but can’t be sure. A leaping fish, perhaps, or a surge making it through from Hell Bay? Or could there be something else in here with me?
A few seconds later there’s a more pronounced slap-splosh and, yes, something dark arcing above the kelp. Unseen lurkers are a familiar anxiety for wild swimmers, and bobbing here between the high walls above a seething space where something fast and powerful is moving about feels disconcertingly like the trash compactor scene in Star Wars: A New Hope.
I almost yelp when a slick black shape rises – fast, smooth and serpentine – considerably higher than my head. I meet a navy reptilian eye, a long, yellow-hinged beak. A demon clown cormorant. I am swimming in what must be a perfect fish trap. It regards me with the faintest suggestion of a smirk, then disappears as smoothly as it came.
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