Inhabited over the centuries by hermits, monks, farmers and lighthouse keepers, the remote Calf of Man is both a time capsule and frontier of seabird regeneration efforts.

Down at the harbour, it was time to go sailing. Port Saint Mary, near the Isle of Man's south-west tip, was half-empty; the only discernible morning activity on the jetty the seagulls perched on empty lobster pots with eyes fixed on the boats at anchor. Only one of these was showing any sign of movement, and with its engine ticking over and the stink of diesel in the air, the two-man crew onboard set their little motorboat on course across the open sea. Their destination? One of Britain's most isolated islands, hemmed in by precipitous cliffs and tempestuous waters.

Found less than half a mile off the south-west coast of the Meayll Peninsula of the Isle of Man, the Calf of Man is that rarest of destinations in the British Isles: a thrilling place, but one that's often impossible to get to, no matter the season or how hard you try.

Chiefly, it is a place lorded over by migratory birdlife, including the sooty black and white Manx shearwater, one of the longest-lived UK bird species. This historic island of two ruined lighthouses is also almost uninhabited, except for the two wildlife wardens and two intermittent volunteers who steward the bird observatory from March to November. Outside those months, the island lies empty.

But the racing tidal currents of the Irish Sea and the swirling Calf Sound, which separates it from the British Crown Dependency, frequently make it a treacherous crossing. At times, in gales and rollercoaster tides, the island can be cut off for weeks, and just below the surface, the seabed is littered with shipwrecks. Among them are a 160-tonne brig from Liverpool, a cargo vessel from Glasgow and a French schooner – which means getting to the Calf of Man has all the hallmarks of a pilgrimage.

At the boat's helm that morning was Steve Clague, a Manx sailor who has seen more than his fair share of bad weather. Like his father before him, who'd made the same boat trips to the Calf of Man for 40 years, he believes the island sets people dreaming because it often can be so hard to get to.

"Last July we didn't set sail once," Clague told me, one of the 10 passengers on that day's 4.5-hour sightseeing round trip. Around us, the sea gleamed silver-blue in the morning sun, and scanning left and right, there was no sign of the dramatic cliff-hemmed seascape that would soon take over. "The Calf is a unique, beautiful place. Unspoilt and always transforming. The trick isn't to come once but to see it in all its different moods. It's a little time capsule."

Plan your trip:

Small sightseeing boat trips from the Isle of Man to the Calf of Man operate daily from May to September, weather and tides permitting.

© BBC