It’s changed again!” the seven-year-old says as we hit the snowline at about 1,400 metres. He’s impressed that such a small island can contain so much. The mountains close in and the road bends sharpen; we’ve only been in the car for an hour, but this morning’s beach feels a long way away. The constantly shifting scenery keeps restlessness at bay – no mean feat with a seven- and a nine-year-old in the back seats.

Lying between mainland France and Italy in the Ligurian Sea, and often referred to as the Île de Beauté, Corsica is renowned for its geographic variety: two-thirds of the island is a crumpled mass of granite peaks, torrents and valleys formed 250 million years ago.

The continuous mountain range carving a spine down the middle of the island is the setting for one of Europe’s most spectacular hiking routes, the GR20. It’s also one of the continent’s most challenging, but a little research reveals that much of the route is accessible in bite-size chunks which are doable with small children. With about 200 beaches, coastal paths and storied ports framing the peaks, it’s a dream combination for an active family holiday.

Even better is the fact that we can experience such epic landscapes without jumping on a plane. With the help of no-fly tour operator Byway, we add three days to our trip, making a leisurely round trip by train and overnight ferry, adding a sense of adventure that flying could never provide. We break the journey in Cassis in southern France, falling head-over-heels for the laid-back harbour and nearby Parc National des Calanques, before boarding a coastal train to Toulon.

From there we sail overnight with Corsica Ferries to the capital, Ajaccio, on the island’s west coast. The journey itself is fun. After enjoying the onboard disco and looking out for fin whales by moonlight (the Ligurian Sea is a migratory channel), we sleep soundly in a cabin for four. Disembarking at dawn feels exotic. Palm trees sway above silent streets and snow-capped mountains glow under the rising sun. Our first hotel, La Pinède, is a 15-minute taxi ride west along the coast.

Later that day, we take a bus to the Pointe de la Parata headland to scramble on rocks, chase lizards and get lost among a kaleidoscope of greens pock-marked with white and pink rockroses. It’s our first glimpse of the maquis – scrub that covers more than a third of the island. Made up of myrtle, thyme, honeysuckle and other sweet-smelling hardy plants, it is particularly lovely from mid-April, when we’re here, until late June.

Ajaccio itself offers a different kind of history lesson. Napoleon Bonaparte was born here, and as we’re heading to his family home, now a museum, the kids lure us into Naporama, where the military leader’s life story is told in more than 800 Playmobil figures. It’s an enthralling enough Napoleon fix for one day. “I’m not sure he was a great guy,” the nine-year-old comments, despite our guides’ best efforts to persuade us otherwise.

From Ajaccio, we explore the island’s northern half on an itinerary that takes in a bit of everything with minimal distances (our longest drive is under two hours). For those with more time, the whole thing is doable by rail, thanks to the Chemins de Fer de la Corse. But as we’re travelling off-season, when trains aren’t as frequent, we hire a car and take turns to jump on board for some sections of the route.

Our second overnight is at a Wes Anderson-esque, pastel-pink guesthouse, U Castellu, in Vizzavona, an hour inland from Ajaccio. The GR20 passes moments from the hotel, so we follow its red-and-white waymarkers to the Cascade des Anglais waterfall, squealing with delight as we discover mossy plunge pools fit for the most mythical of worlds. An evening feast of stewed pork (“Mountain pig!” enthuses the chef) and eggs baked in cream cheese awaits us at the hotel. It may not be the lightest cuisine, but everything is proudly local.

We set off early the next morning to follow the GR20 in the other direction, climbing Bocca Palmentu (1,640 metres). Over three hours, we ascend through dense pine forests, passing sporadic clumps of crocuses and negotiating snow-laden paths to a heather-clad plateau. The route can get busy with hikers in peak season but is quiet in April: it seems we’re as likely to be disturbed by wild boars as by people.

The next stop is Corte, the island’s cultural heart. Two of us take the train from Vizzavona, pirouetting along steep-sided valleys on the 19th-century Trinichellu (little train) route. The town is surrounded by towering peaks and home to an impressive citadel, so it’s easy to see why nationalist leader Pasquale Paoli made Corte his capital after declaring independence from Genoa in 1755. It still exudes a quiet sense of rebellion: locals cackle over glasses of Cap Corse (a bittersweet fortified wine) in sunny squares from 10am.

Musée de la Corse, in the citadel’s former barracks, is a mix of anthropology and history – perhaps reflecting the island’s longing to make peace with its past while holding on to its unique culture.

Our boys, however, are more enthralled by the fortress’s ancient nooks and crannies. Church bells ring, kites soar overhead and house martins flit between terracotta roofs; we wonder whether we’ve slipped into a different century.

Home for the next two nights is Les Jardins de la Glacière, a hotel sandwiched between rock and river in the Vallée de la Restonica. It’s a renowned swimming spot, so we brave the chilly waters before trekking up to a glacial lake, Lago di Capitello.

Then the landscape changes again. Tall Corsican pines, bleached boulders and rusty refuge roofs remind me of the Rocky mountains.

“I’m Spider-Boy!” the seven-year-old shouts as he clambers up rocks. After picnicking by the frozen lake at the top, we slide back down snowy paths on our bottoms.

We are planning some beach time at our next stop – Calvi, capital of the Balagne region in the north. But we’re in no hurry and meander there along the Route des Savoir-Faire de Balagne, which showcases more than 40 small-scale artisans scattered among enchanting hilltop hamlets.

“It helps get the tourists away from the beach,” a potter in pretty Pigna says after inviting us to watch his wheel in action.

Calvi’s slick waterfront feels a world away again. The town has it all – fancy yachts, a citadel plunging into a cobalt sea and a three-mile white-sand bay. After dropping bags at Hôtel Casa Bianca, we hit the beach.

On the next day, we make the most of the coastal railway, trundling past gnarly pines to Plage d’Aregno for lunch. We can hardly believe our luck when we spot dolphins offshore and a golden eagle overhead.

Too soon, the ferry back beckons, and we head to our final stop, the town of Bastia on the north-east coast. Less glamorous than Ajaccio, Bastia has charm in spades. We while away a day playing cards in the old citadel as hundreds of swifts screech overhead and kids play football in cobbled squares.

Burnt patches on the road tell of recent riots and the island’s ongoing quest for independence. The past comes tumbling into the present, leaving us with more questions than answers.

It’s a neat reminder that Corsica’s beauty may lure visitors for the first time, but it’s the layers beyond the landscapes that will bring them back. Mirroring its complex past, Corsica manages to be proud, aloof, complex and plain-speaking all at once: character traits that perhaps bubble up best while going slow in the quieter months, adding a little depth to an ideal family adventure.

The trip was provided by Visit Corsica. A nine-day overland itinerary to Corsica and back, including all transport and accommodation, costs from £797pp with Byway