While many Mediterranean resorts hibernate, a new air link to Croatia's capital, Zagreb, can connect you with lively Adriatic alternatives

In winter, deprived of the colour and charisma of people from planes, the islands and coastal resorts of the Mediterranean can end up looking a bit forlorn, just like our gardens. It's for this reason that airlines re-focus their efforts on flying to destinations popular with city-breakers and skiers. This week easyJet launched a new service from Gatwick to the Croatian capital. On the face of it this looks like the basis for a short stay in Zagreb, but it also gives access to a choice of interesting resorts, Opatija and Zadar, on the Croatian Riviera.

A new motorway that sweeps past Zagreb's airport enables visitors easily to reach Opatija – now only 90 minutes away. When Austria-Hungary was a flourishing concern, Opatija was the winter retreat of choice for wealthy Viennese: it was the closest bit of coast to the capital, just 200 miles as the imperial eagle flies.

The resort is set on a curving piece of shoreline that climbs quite steeply into forested mountains, and its hillside setting means that a great many properties have a sea view out over the Kvarner Bay. Once the railway arrived here back in the 1870s, the villa-builders were quick to cash in, particularly when the Austrian government declared Opatija the first climatic health resort on the Adriatic, thanks to its particularly mild winters. Thereafter the aristocracy decamped here en masse as soon as it got chilly in Vienna.

Opatija still has an old-money feel, rather like "the Nice of the Croatian Riviera". There are excellent fish restaurants, and some glorious villas are still in private hands. One or two are the dowager duchesses of the hotel world, particularly the once-grand Hotel Kvarner, with its high ceilings, faded damask, echoing corridors and the aura of Murder on the Orient Express. It is presently closed for the winter, but re-opens in time for Easter. The hotel's modest rates (just €60 a night for two people, including breakfast) reflect its unmodernised state.

In common with much of the nation's coast, Opatija does not boast much of a beach – but the seafront is basically one long promenade, with tea-rooms, botanical garden and bandstand and a strong sense of tradition. The dancer Isadora Duncan used to come to Opatija in search of sexual adventure, while the Viennese used to have their cake sent here by train. I suspect that these days young lovers are not so easy to find, but Opatija is still a place for a sachertorte with a sea view.

Zadar, on the opposite site of the Kvarner Bay (and two hours' drive from Zagreb), is a different matter. Far older, and once the capital of all Dalmatia, it nevertheless manages to feel much more contemporary. Tourism is just a part of its portfolio. This is a place of students, of shoppers, of entrepreneurs and visitors from the offshore archipelagos, seeking the bright lights. If Duncan came looking for young lovers today, this would be the place to go.

Built on a short string of islands, Zadar's first settlements were eventually merged to become a single bent thumb of land ringed with ramparts and reached through a chain of fortresses, with a superb natural harbour on its inland side. Unfortunately, this formidable fortification was also its weakness, for every passing superpower recognized its strategic value. It was forever being sacked and sieged and it suffered particularly heavily during the Second World War.

For much of the 20th century Zadar languished, neglected. The town had a problem deciding what to do about all the Roman and Venetian remains that the bombing had uncovered. The original Roman Forum is still a strangely vacant space in the heart of the pedestrian area. But the last couple of decades have witnessed a renaissance, and now Zadar likes to describe itself as the California of Croatia. It is growing fast, and attracting young entrepreneurs. Andnext month, non-stop flights from Stansted resume. (If you book by midnight tomorrow, Ryanair has plenty of availability from 27 March onwards at just £16 return, including tax.)

The Old Town is still a quirky mix of antique rubble, Romanesque cathedral, narrow-laned Venetian trading port, Austro-Hungarian resort and 1960s Communism. That strange concoction makes it an unpretentious place; the coffee shops are animated and ferries and fishing boats come and go from the quay. There's gossip in the lanes, and the market is busy with smallholders from outlying islands who have come to the mainland sell their olive oil and cheese. And because of this local clientele, prices in the restaurants are less than half their equivalent in Dubrovnik or Zagreb.

There's a whole world just offshore. Zadar County includes 24 big islands, and a further 35 which are uninhabited. And then there's the Kornati archipelago, a spectacular National Park composed of an otherworldly landscape of some 150 spangles of land, covered in sage and feather grasses that look like brushed velvet.

But those are summer destinations. In winter, the place to be is the furthest tip of Zadar's Old Town promontory, from where ferries leave for Italy. This is the location of the town's most spellbinding innovation: its sea organ, whose giant pipes are built into the promenade. Whenever the swell or the wash from passing boats hits the shore it blows air through these pipes, triggering a haunting series of notes that fills the air all around.

Not everyone likes it. My companion thought it sounded like the plaintive calls of a trapped herd of sea-cows, corralled beneath the concrete. I thought it sounded as if mythical feet were working the pedals of a celestial cathedral organ, and we were receiving musical messages from elsewhere – the sound of nature speaking to man.

Travel essentials

Getting there

Croatian Airlines (020-8745 4683; www. croatiaairlines.com) flies from Heathrow and Gatwick to Zagreb; easyJet (0905 821 0905; www.easyJet.com) flies from Gatwick. Ryanair (0871 246 0000; ryanair.com) flies from Stansted to Zadar from 27 March.

Staying there

Hotel Kvarner, Opatija (00 385 51 271 233; www.liburnia.hr). It re-opens on 14 April;

doubles start at €60, including breakfast.

Hotel Bastion, Zadar (00 385 23 494 950, www.hotel-bastion.hr). Doubles start at €130, including breakfast, during March; the rate increases to €156 from mid-April.

More information

Opatija: www.opatija-tourism.hr; Zadar: www.visitzadar.net; Croatian National Tourist Board: 020-8563 7979; www.croatia.hr