At 6.30am, I walk to the empty beach at Belvoir Bay. The sand is soft, the sky is pink, Normandy lines the horizon. The only sounds are the murmur of the waves and the piping of oystercatchers. I plunge into the sea. Immediately, the cove is filled with terrible swearwords: I force myself to stay in the water, spluttering and cursing but growing less cold with each swimming stroke. Hours later, sipping coffee while overlooking another deserted beach, my skin is still zinging and my mood is irritatingly smug.

A dunking in the bay is an apt way to start the day on Herm. The tiny, comma-shaped Channel Island – stretching just under 1.5 miles from top to bottom, and less than half a mile across – feels like a place cut adrift. This is emphatically a good thing. The island has a permanent population of 65 and a history that yawns back to the Neolithic era. Puffins breed on its southern cliffs; rabbits nibble in its flower meadows; migrant warblers cluster in its pine groves. You’ll find no cars, or even bikes, and the primary school has four pupils. The island’s name sounds like a hesitation, but its pretty hills, woods and beaches demand to be savoured in the here and now.

Well, most of the time. Shortly after my arrival on the 15-minute boat crossing from Guernsey, a spring downpour brings gale-force winds and horizontal rain. It gives me the chance to do an inventory of the harbourside buildings – one hotel, two pubs, a handful of stone cottages, an old prison big enough for one – and to watch the waves being whipped into a dark fury. When the storm passes and the sun returns the island feels washed clean, the sands flowing white into a turquoise sea. I’m here for a short visit, partly to find out more about Herm’s drive to become less carbon-reliant.

“I always say the scenery is a mix between the Caribbean, the North York Moors and the Pembrokeshire coastline,” says the island’s CEO Craig Senior. (Yes, an island with a CEO: Herm is owned by the States of Guernsey, which leases it for use as a visitor destination. The current tenants are former Guernsey residents John and Julia Singer, who had their first date on Herm in the mid-90s and took on the lease in 2008.) Craig is a gregarious Rotherham United fan, here since 2019 with his wife and children. He is tailed by his dog, Harvey, who has the run of the island and is possibly the world’s happiest sproodle. “Herm’s part of the British Isles, it’s part of the Channel Islands, but more than anything it’s just Herm,” he says.

There’s simultaneously lots to do – eat, drink, swim, walk, kayak, birdwatch, jog, mooch, poke your nose into the millennium-old chapel, stargaze, sleep – and little in the way of diversion. If that sounds contradictory, welcome to Herm. As well as the White House hotel, which has sea views and serves classy evening meals, visitors can stay in self-catering cottages or at one of two campsites. The island knows how to draw a crowd in summer (among its various events, Utah Saints played a gig here in 2022, with DJ-producer Sasha doing the same this September), but in the shoulder season it feels like a seaborne secret.

It’s also somewhere that is trying to do things the right way. Herm has been making strides to become more eco-friendly over the last couple of years. The Isle of Herm ferry service from Guernsey runs on biofuel – hydrotreated vegetable oil – and 60% of the boilers on the island have been converted to do the same, with the rest to follow. Solar panels are at campsite washblocks, and a tender is out for a solar energy farm in one of the more isolated meadows. “We’re on a bit of a journey,” says Craig.

While there is more to be done to reduce the island’s footprint, he is proud of what has been achieved. Six nature trail boards have recently been erected around the coast, a granite quarry has been reinvented as a zen garden, and all glass bottles are now crushed to provide hardcore for the shaggy-hedged lanes that thread the island.

Craig suggests I take a stroll around Herm’s perimeter. The coastal path looks simple but hides nooks within nooks. The north of the island is low and sandy, dotted with rock pools and ancient tombs, while the south is high and wooded. There are bluebell drifts and deep caves, eucalyptus thickets and headlands that attract kestrels, gorse plateaux and hulking sea stacks. There are puffins in Puffin Bay and shells on Shell Beach. The ferry is coming into Herm’s harbour when I start the walk, and again when I finish two hours later.

I get chatting to the skipper, Chad Murray, who has sailed these waters since doing a Duke of Edinburgh award, when he was 12. He’s Guernsey-based but used to come to Herm for Christmas with his children, bringing his own spruce tree across on the boat. “I love it over here. It’s just calming. It’s also a designated Ramsar site, which means it’s a wetland of international importance,” he says. Murray is planning on introducing summer boat tours around the island, to allow people to spot seals, seabirds and other marine life.

I spend the next two days moving at Herm pace. I rent a kayak and bob along the east coast, staring at Sark as terns dive into the waves for fish. I meander around the lanes, listening to wrens and chiffchaffs singing in the blackthorn. I watch guillemots flying low over the sea, past the humped neighbouring isle of Jethou. I learn that the woman who runs the beach cafe is also one of the island’s firefighters (three callouts in five years, though nothing calamitous), and that the man who looks after waste management is also the island’s police officer (no one can remember the last arrest). And I try Channel Island ales at the Mermaid Tavern, where the ceiling is covered in pump-clips and cabbage palms stand over the beer garden.

The Singers are passionate about looking after the island’s natural environment. This is evident when I join five residents for a beach clean, something arranged several times a year. It’s reassuringly fruitless. We spend 45 minutes walking two beaches and find a couple of washed-up plastic stirrers, a length of ship’s rope and a copper oxide-coated penny from the reign of King George VI.

Previous custodians of the island have been similarly committed to keeping Herm unspoiled (with the possible exception of the Prussian prince who held the tenancy in the early 1900s and introduced wallabies). The most longstanding tenants were Peter and Jenny Wood, here for almost half a century from 1949. Jenny summed up Herm as a place “where time has trod lightly and the passing centuries made little impress on the lovely contours”. Well, quite. The island is a joy. Just brace yourself if you’re taking a sunrise dip.

The White House hotel has doubles from £145 B&B (from £237 in July-Aug). Self-catering cottages from £261 for three nights (or from £1,204 for minimum seven nights in July-Aug). Equipped camping from £85 a night in a tent sleeping six to eight. Return crossing from Guernsey on Isle of Herm ferry £16, herm.com / visitguernsey.com. Condor Ferries has regular sailings from Poole and Portsmouth to Guernsey, from £80 return for a foot passenger