With 15,000km of coastline to choose from, you can take your pick from fjords, beaches, surf or reefs.

How extensive?

You are never more than 120km from the coast in New Zealand, poised as it is between the Tasman Sea to the west and the Pacific Ocean to the east. And with a third of the coast devoted to beaches, you're also never far from a beach. Between them, the North and South Islands, and many smaller isles, offer one of the world's longest coastlines: some 15,000km of irregular bays, beaches, harbours and fjords. Unmapped until Captain James Cook's first voyage in 1769, two-thirds of the coast is now publicly accessible thanks to laws passed in 2004.

Start off in New Zealand's largest city and sailing capital, Auckland, to get your bearings and make a racing start. Besides being the country's main international gateway, it is a beautiful city in its own right. Speeding past the skyscrapers, volcanic cones, coastal suburbs and white-sand beaches gives a quick, exhilarating introduction to some of the nation's most densely populated shores – though this is a relative term in a country twice the size of England with a population half that of London.

Auckland is known as the City of Sails. You can take this slogan literally aboard one of the elite America's Cup racing yachts that offer two-hour pleasure-boat trips around Auckland's beautiful harbour. Through Sail New Zealand (00 64 9 359 5987; www.sailnewzealand.co.nz) you can sign up as crew, or sit back and let others set the sails, for NZ$135 (£46).

Sandy shores and seabirds?

About an hour south of Auckland, the black sand dunes of Muriwai, Bethells, Piha and Karekare beaches are perfect for a day trip. As with coastal experiences anywhere in the world, the weather sets the tone. On grey days, seagulls, wind-blown spinifex and wild rabbits can be the only signs of life on the black dunes. But the sparkling sands act as magnets when the sun is out, with thousands flocking in particular to Muriwai, the longest beach. Treated as one big adventure playground by locals, it offers swimming, surfing, coast and cliff walks, mountain biking, paragliding, horse trekking, land yachting, and kite fishing.

Wheeling around overhead are paragliders, who jump from the cliffs to ride the air currents, and yellow-headed gannets, one of the many seabirds that, along with penguins, albatrosses, petrels and shags enrich New Zealand's rugged shores.

I'd like to stay a while

Staying in a "bach" – short for bachelor pad – or holiday cottage by the sea is the quintessential New Zealand summer holiday experience. For generations, holidaymakers made do with the same basic, corrugated iron bachs. But in the 21st century, thousands of designer bachs have joined the ranks of spartan, brightly painted 1950s originals. Bach-hopping around the country's coasts is becoming popular, with websites such as www.bookabach.co.nz and www.holidayhouses.co.nz offering a selection of bachs for about NZ$100 (£34) a night. Go south to Lake Tekapo and Lake Hawe for views of big blue glacial lakes and the Southern Alps, snow-capped for much of the year, from your living room. Or, for classic bachs metres from horseshoe-shaped white-sand beaches and gnarled, red-flowering pohutakawa trees, visit secluded Matapouri, on the north-east coast four hours from Auckland.

And underwater?

The subtropical reefs of the Poor Knights Islands, off the north-east coast of the North Island, were rated one of the world's top 10 dive sites by Jacques Cousteau. Fed by a warm current from Australia, the sheer underwater cliffs, caves, chimneys, tunnels and arches formed out of a chain of volcanoes that eroded millions of year ago are a haven for tropical fish rarely seen in New Zealand's largely temperate water. Mixing in with the spotted black groper, mosaic moray and Lord Howe coral fish are dolphins, stingrays, migrating whales, orca and the odd tropical Hawksbill turtle.

With water temperatures hitting 25C in summer, no real current nor long surface swims to contend with, and visibility good up to 30 metres, the Poor Knights are dived, snorkelled and swum year-round.

Any wrecks?

Plenty of them. There have been an estimated 2,300 shipwrecks since European settlement began in the 1790s. The country's most notorious wreck was an act of state-sponsored terrorism. In 1985, Greenpeace's flagship anti-nuclear boat, Rainbow Warrior, was sunk while docked in Auckland harbour by limpet mines laid by two French government agents. Three years later, she was towed north and re-sunk as a memorial, and can now be dived or snorkelled off Northland's Bay of Islands. Technicolor purple, blue and orange anemones cling to her rails, while seahorses and big fish such as golden snapper, kingfish and John Dory circle around.

Independent charter boats set out from Matauri Bay, the closest boat ramp to the wreck; tour operators also offer package deals. First Light Travel's four-day tour departs from Auckland once or twice a month, taking in Rainbow Warrior, Poor Knights, and two nearby naval wrecks; equipment, transport to and from Auckland, three nights' accommodation, and breakfast and lunch, from NZ$1,675 (£570) for one or NZ$1,475 (£502) for two (0871 474 0083; www.firstlighttravel.com). First Light's sister organisation, Globaldive (00 64 9 920 52000; www.globaldive.net) offers internationally recognised beginners' two-week PADI Open Water dive courses for NZ$449 (£152), available twice a month, or tailor-made private courses from NZ$899 (£306) per person.

The best surf?

At any given minute, on any given day, thousands of waves are crashing on to hundreds of surf beaches across New Zealand. But experts say that slightly raffish Raglan, on the North Island's east cape, has earned its Surf Capital title for the consistently steep, fast waves that smash onto its black sands. Besides all the visiting surfers, "Rag Town" is also a thriving coastal community, whose 3,500 resident surfers, Bohemians and down-sizers have their own Arts Council, lager, knitting circle, and gigging bands.

Manu Bay, 8km from Raglan township and home to one of the planet's longest left-hand breaks, is the star attraction. Ten minutes' drive south of the town are the consistently good waves of The Indicators, and 1km beyond that is a third hotspot, Whale Bay, home to the Raglan Surf School (00 64 8 825 7873; www.raglansurfingschool.co.nz). Its instructors offer a money-back guarantee if beginners aren't up and standing by the end of a lesson. Half-day introductory classes and two- to five-day surf-school packages range from NZ$140 (£47) to NZ$300 (£102), accommodation included. In winter, the school offers free bowls of home-made soup and evening saunas. Not to be left out, Raglan's Surf Dames school, set up by women surfers, specialises in women-only "luxury surf retreats" that offer lessons, massages and beauty treatments.

Can I go fishing?

Snapper, marlin, kingfish... New Zealand's big, bold ocean fish have put its shores on the recreational and sport fishing map. But it's the country's large, abundant freshwater trout that u ufire most enthusiasts' imaginations. Whether you want to stand waist deep in a river fighting a nine-pound rainbow trout on a four-pound nylon line, or sit back with a beer on a boat and try casually to reel them in, New Zealand's largest lake, Taupo, in the middle of the North Island, offers superb fishing for brown and rainbow trout alike. As well as the ubiquitous bachs ringed around it, there are several hotels in Taupo itself. The luxurious Huka Lodge (00 64 7 378 5791; www.hukalodge.com) lies 4km away on the shores of the Waikato River. Huka has hosted visiting royals and celebrities from Diana Ross to Ru pert Murdoch. Its doubles range from NZ$695 to NZ$1,190 (£236 to £405) including breakfast. Staff can arrange fly fishing, jet fishing and raft fishing expeditions to dozens of nearby lakes and rivers, such as the Tongariro River, the trout's major spawning river.

There are a host of other local guides, including Central Plateau Fishing, which runs tours from NZ$290 (£100) (00 64 7 378 8192; www.cpf.net.nz). Or simply head to a sports shop and pick up a road map and a fishing licence, NZ$15 per day, issued by the Fish and Game Council (00 64 4 499 4767; www.fishandgame.org.nz), and strike out by yourself.

A walk on the wild shore?

Strange as it may sound in rugby- and bungee-obsessed New Zealand, walking for days along deserted coasts to stare out at empty horizons is also a popular national pastime. Some of the most beautiful coastal hikes, marketed as "Great Walks" by the Department of Conservation, are booked solid in summer by nature-loving city-dwellers chasing what local poet Bruce Manhire has referred to as "the edge-of-the-universe" experience.

To clear your head, try less-frequented tracks that skirt across hard-to-access private stretches of coast. One such path is Marlborough's Queen Charlotte Track. Running like a rollercoaster along the top of high, rounded green ridges in the north of the South Island, the wide, gently undulating track gives a bird's-eye view over the narrow fingers of land that stretch into Queen Charlotte Sound's calm green waters.

Covering almost the entire sound, the 71km track takes four days and three nights to walk, or two days on a mountain bike, available to hire from NZ$45 (£15) per day (00 64 3 577 8080; www. qctrack.co.nz). But you can take it easier: split into easy, two- to three-hour sections, between isolated bays, the walk gives panoramic views towards Cook Strait, which separates North from South Island, without the effort of steep climbs or descents. The route can be broken, or added to with additional side tracks, from various campsites and resorts such as pretty Punga Cove (00 64 3 579 8561; www.punga cove.co.nz) at Endeavour Islet. This location offers a full range of chalets, suites and backpacker accommodation, as well as dolphin-watching tours, barbecues and even pétanque. Rates for accommodation are good value: backpacker dorms from NZ$35 (£12) per person, chalets from NZ$170 (£58), suites from NZ$300 (£103).

Something more active?

Tucked away to the east of the Marlborough Sound in the country's smallest national park, the South Island's 51km Abel Tasman coast path is New Zealand's highest-rated beach walk. Consequently the track is jammed with hikers in summer. To avoid the crowds, emulate Abel Tasman, the Dutch explorer whose 1642 voyage put the area's shores on the map: take to the seas.

Even though you are likely to find yourself in a plastic sea kayak rather than a tall ship, paddling alongside the stunning white sand beaches and pink granite outcrops gives a sense of space, and allows a closer look at passing seals and dolphins. Half a dozen local firms hire kayaks. Southern Exposure (00 64 3 527 8424; www.southern-exposure.co.nz) offers one- to three-day catered and guided trips from NZ$120 (£40), or a four to five-day "freedom rental", where you store your own food and bags in the watertight hull, for NZ$180 (£61). Overnight stays are at the DoC-run Abel Tasman campgrounds and huts, or private such as the beachfront Torrent Bay Lodge.

To continue exploring, park up on the beach at the end of the Abel Tasman and then head inland into the adjacent Heaphy Track, also managed by DoC as a Great Walk (00 64 3 525 8026; www.doc.govt.nz), to steal up on the South Island's wild west coast. Crossing from east to west across the island's northwest corner, the four- to six- day tramp covers creeks, brooks, and waterfalls. After days of hiking through quiet red tussock grasslands and silver beech forests, the roar of the Heaphy River surging out into the west coast's crashing waves is almost deafening.

Fjords and falls?

Milford Sound's steep grey granite shores are unlike any others. For a start, they are dominated by the jutting, symmetrical, silhouette of 1,695m high Mitre Peak, one of the highest sea cliffs in the world. In addition, two permanent waterfalls, and a number of temporary ones, thunder down the sides of the sound's narrow sea-filled valley, located in virtually uninhabited southwest Fiordland, 15km inland from the Tasman Sea

A host of tour operators run cruises in Milford, and nearby Dusky and Doubtful sounds, from Te Anau, two hours away by road. For a peek at life under the surface, Red Boat Cruises (00 64 3 441 1137; www.redboats.co.nz) can also include a stop at the Milford Deep underwater observatory (00 64 3 441 1137; www.milforddeep.co.nz), for around NZ$80 (£27). Its viewing walls, 10m under the surface, showcase the normally-deepwater black coral that grows in the fjord's shallows because of a geographic quirk related to the area's high rainfall. The sound's 11-legged sea star and the sex-changing scarlet wrasse fish can also be seen swimming about with octopuses and seals.

How do I get there?

The only airline with direct flights from the UK is Air New Zealand (0800 028 4149; www. airnz.co.uk), which has a daily service both eastbound and westbound from Heathrow, via Hong Kong and Los Angeles respectively; you can see the shores of the Atlantic, Pacific and South China Sea by opting to travel out one way and back the other. Fares start at £659 return, taking advantage of a special discount to celebrate 25 years of flying from London. Connections to dozens of other New Zealand destinations are available. Other leading airlines include Cathay Pacific (020-8834 8888; www.cathaypacific.com), changing planes in Hong Kong; Emirates (0870 243 2222; www.emirates.com) connecting in Dubai; Qantas (08457 747 767; www.qantas.com.au) with a change of plane in Sydney; and Singapore Airlines (0844 800 2380; www.singaporeair.co.uk) changing in Singapore.

Additional research by Rosie Scammell

The coast by camper van

For a quick, concentrated hit of blinding white sands, deep blue sea and green rainforest, try the eastern Pacific Coast Highway (00 64 7 867 9075; www.pacificcoast.co.nz). The entire five-day suggested route edges off along the Bay of Plenty and around the jutting East Cape down to Hawkes Bay, but the initial Coromandel part of the route has variety enough as it connects the dots between small, ruggedly charming seaside towns.

Hire a motor home from operators like Maui (00 64 9 275 3013; www.maui-rentals.com), which offers two-berth campers for around NZ$400 (£136) for six days, and hit the ocean coast south from Auckland. After about two hours the route crosses the single-lane Kopu swing bridge over the Waihou River, just outside the old gold-mining town of Thames, and starts up the Coromandel's 400km of shoreline.

State Highway 25 then runs along the peninsula's east coast to Coromandel township, before turning inland and winding up the Coromandel Ranges. Crossing through a narrow strip of sub-tropical rainforest towards to the west coast, the road then drops back down to the shoreline. Break the journey with a 10-minute detour from Kuaotunu Beach on a gravel coast road that leads to the secluded bays of Otama and Opito.

Heading back south, Cooks Beach has 3km of soft white sand. Hahei Beach is also the access point for a coastal walk into the sheltered Cathedral Cove marine reserve. Offering yet more yet white sand, this time framed by white cliffs and caves, Cathedral Cove Dive (00 64 7 866 2955; www.hahei.co.nz/diving) hires snorkelling and dive equipment, as well as PADI courses. You can also board the glass-bottom Seafari II, taking a two-hour trip to scan for crayfish (www.glassbottomboatwhitianga.co.nz).

Hahei also has a macadamia orchard (00 64 7 867 1221; www.cathedralcovemacadamias.co.nz). Like other cottage industries that have flowered in remote locations the macadamia farm sells its own produce in the form of nuts and bottles of oil. It also offers accommodation. Cottages sleeping up to six start at NZ$130 (£45) per person for two, additional guests NZ$15 (£6) each.

Underwater world

Four or five hours by ferry from Auckland, isolated Great Barrier is the largest island off the coast of New Zealand's North Island. The size of the Isle of Wight, it has crystal-clear waters and a stuck-in-time ambience.

Ferry services on Fullers (00 64 9 367 9111; www.fullers.co.nz) and SeaLink (00 64 9 300 5900; www.sealink.co.nz) run regularly from Auckland for around NZ$100 (£34) return.

"The Barrier", as it is known, is home to 850 islanders, all of them on first-name terms. It has done a good job of keeping the modern world at bay. Though there are small airfields, some post to the mainland still travels via Pigeon-Gram. And you'll need to take a torch and carry plenty of cash as there are no street lights, ATMs or banks on the island; locals rely on generators for electricity. Despite this, travelling around is easy. About two-thirds of Great Barrier is public land, and there are 100km of well signposted walking tracks, campsites and bike routes criss-crossing underneath native nikau palms and rimu and kauri forests.

Get back to basics at the Department of Conservation (DoC) campground at Medlands Bay, positioned between farmers' vegetable patches and a gentle surf beach (00 64 9 429 0044; www.doc.govt.nz; adults NZ$9 per night camping), or there are solar-powered beach houses and even the odd luxury hotel to stay in.

The local guiding company Discover Great Barrier (00 64 21 420 935; www.discovergreatbarrier.co.nz) runs three-day walks around the island November to May, for about NZ$250 (£85) per person, or there are hire cars and buses for the sometimes-rocky coast roads between settlements.