From my balcony high in the hills, I watched the sun set over Lake Iseo. The water was blazing, the colour of copper. A final stream of molten gold pulsed over the waves like a searchlight, catching a tiny sailing boat in its main beam. The birdsong in the chestnut forest all around me had subsided. You could hear yourself breathe.
How on earth, I wondered, had I never heard of Lake Iseo before this visit? In truth, I hadn't even known how to pronounce it ("Izz-ayo" – to rhyme with mayo). The smallest of Lombardy's four major lakes, it is often bypassed by foreign visitors in favour of its more glamorous big sisters: Garda, Como and Maggiore. What a gem I'd been missing. The Italians, of course, have been quietly holidaying here for years.
Shaped like a scythe, Lake Iseo (also known by its Latin name Sabino) cuts a deep blue swathe at the foot of the southern Alps. It's about 25km long, ringed by dense green forest, and – happily - has escaped much of the over-development that has started to urbanise the waterfront of the better-known lakes. It has only three main towns: Iseo, Sarnico and Lovere. A handful of other smaller settlements are dotted around its shore, linked by a pretty coastal road. And, rising dramatically from the water near the lake's centre, is Iseo's crowning glory – the beautiful wooded island of Monte Isola, which peaks some 600m above sea level.
Ferries zigzag around and across the lake, with an even more frequent small boat service (the traghetto) linking the mainland with Monte Isola. Together, these services offer an ideal introduction for a first-time visitor. churches, palazzi, villas and piazze all present their best faces to the water. As you approach a town by boat, all of its colours and treasures are spread out before you.
At the larger towns of Iseo and Sarnico, the watersides are bustling with pizzerias and ice-cream parlours, but swans still drift idly amid the marine traffic. At more rustic Clusane, fishing boats bob next to piles of nets.
Even the smallest of settlements has its share of extravagant buildings. At sleepy Sale Marasino, the Palazzo Martinengo is one of the finest Renaissance mansions on the lake. At Sulzano, elegant 19th- and early 20th-century villas parade their finery proudly on the waterside at each end of the old town.
But there's no need to confine yourself to the water. Lake Iseo is a fantastic place for walkers. Taking full advantage of an itinerary that included stays in three glamorous hotels, I donned my walking boots and set off on what was, for me, a rare adventure. Purists might frown, but the independent walking package offered by Inntravel is perfect for lazy hikers. A taxi delivers your luggage to the next port of call, while you set off unencumbered – armed only with a set of walking instructions and a picnic lunch.
Sale Marasino was my starting point, an attractive village backed by an old quarter with narrow alleyways, old-fashioned lamp posts and quaint houses. The charming Hotel Villa Kinzica, the first of my three lake-view hotels, is by the water-front.
Above the village is the Strada Valeriana, a footpath that follows the route of an ancient road and winds above the shore among meadows, vineyards and olive groves. With the sun at my back and butterflies around me, I ambled along the stretch of the route that led south to Sulzano, passing over lake views so stunning that I felt as if I'd wandered into a painting. Even a spring shower failed to spoil the magic.
From Sulzano, it's the shortest of traghetto hops to Monte Isola – only 800m away from this point on the shoreline. Car-free Monte Isola is apparently the biggest island within any European lake, and is designated in its entirety as one of the most beautiful "villages" in Italy. You arrive in Peschiera Maraglio, a tiny fishing settlement with an array of ice-cream coloured houses on the waterfront, and a wonderful jumble of lanes called tresandei. The jetty is festooned with flowers and Italian flags, and miniature cypress trees grow from pots set below the waterline along the promenade.
Visiting Peschiera feels like being ferried into a different era. You realise the lake is a place of work, that people's homes and lives are linked organically with the water. There are almost no street names, just house numbers. Dwellings are connected to each other by arches, vaults and stairs – and to the lake itself by courtyards where boats are still built and nets repaired. Out on the promenade, fish are salted and hung out to dry. Back from the waterfront, fishing tackle rests for the day in quiet old arcades, and crumbling porticoes are strung with freshly washed linen.
Monte Isola is a paradise for walkers. A gentle option from Peschiera is to head north along the coastal road or (perhaps more prudently, to avoid the ubiquitous scooters and cycles) to take the mountain track above the shoreline. This leads to Carzono, another pretty waterfront settlement. But whatever you do, try not to miss the spectacular climb (by mule track) from the village of Cure to the Madonna della Ceriola chapel, which lies in woodland at the island's highest point.
Lake Iseo is proud of its cuisine. Unsurprisingly, fresh fish features prominently, with tinca al forno (oven-baked tench, stuffed with bread and herbs and served with polenta) as the local speciality. At the second of the hotels I visited – the fabulous I Due Roccoli, set in the hills above Iseo town – I dined like royalty, justifying the seemingly endless succession of lavish courses with the knowledge that an intrepid walker such as myself must surely need extra fuel.
In truth, the two-hour downhill walk from the hotel to Iseo was a breeze until the end – a gentle stroll through sylvan forests of hazel and horse chestnut, with conker-casings strewn across the pathways like caterpillars and feather-beds of catkins cushioning my footsteps. It wasn't until I hit the final steep descent over uneven cobbles that I was in any danger of burning calories. By this time the periwinkle and wild strawberries had given way to comfrey – always good for sprains, I reminded myself. And down I tottered.
My reward, before heading off to relax in the swimming pool of hotel number three – the Relais Mirabella, which offers panoramic views from above Clusane – was a cold beer in Iseo's main square. Amid a friendly cacophony of clatter as the weekly market packed up for the day, I leafed through an old guide book that I'd picked up from one of the stalls, and came across a stirring quotation from Edith Wharton: "I saw the blue lake far below, hidden in the hills like a happy secret in a stern heart." Wharton visited Lake Iseo over a century ago. How wonderful, I reflected, that it has remained a happy secret.
Travel essentials: Lombardy
* The nearest airport is Bergamo (Orio al Serio) airport, known as "Milan" by Ryanair (0871 246 0000; ryanair.com) which flies there from East Midlands, Prestwick, Liverpool and Stansted airports. Jet2 (0871 226 1737; jet2.com) flies from Leeds/Bradford.
* The writer travelled with Inntravel (01653 617000; inntravel.co.uk), which offers "Secret Lake Iseo – Italy's Little Known Lake" independent walking holidays from £788 per person. The price is based on two sharing, including six nights' dinner, bed and breakfast at three four-star hotels, two picnics, walking maps/route notes and luggage transfers. Flights and transfers, which can be booked by Inntravel, are not included. (Return taxi transfers from Bergamo cost £80 per person.)