What is it about Seattle that makes everyone love outdoor pursuits? Is it the espressos at Café Nervosa? Adrian Mourby finds out

I first came to Seattle in search of interiors. The Rainbow Room where Michelle Pfeiffer sang with The Fabulous Baker Boys, Café Nervosa where Frasier gossiped with his colleagues at the radio station, and that rather chic houseboat where Tom Hanks sat up all night drinking whisky while he was Sleepless in Seattle.

But it was not to be. Griffin, my wife's broad-shouldered cousin, assumed that us folks were over for the kayaking or the kite-surfing, the parasailing, climbing or hiking. "We should spend some down time over at REI, Adrian," he said, laying a great paw on my arm. "They've got a rock face there they call the Spiderman. Do you like climbing?"

Griff and the rest of his tanned, smiling friends typified Seattle to me. They dressed informally, as if they were always ready to set off on a 20-mile cycle ride; their eyes gleamed with health and when they talked about meeting up for a beer in the evening that was what they meant. One beer. By 9.30pm Griff would think it time to turn in. He'd be up at five the next morning, reading his Bible, squeezing his orange juice and setting off for a run round the Pacific Science Center.

Seattle is an outdoors city. From May to October, people get out on the water, the golf course and the city's many miles of cycle tracks and enjoy. The weather may not be all that different from what we have in Britain these days - rain is always a possibility in Seattle, even in summer - but people seem hard-wired to be out and active. It wasn't always so. Griff's father, my wife's uncle, can remember a time before the annual Seafair, which was inaugurated in the 1950s to encourage people to enjoy their city's west coast beauty. "Seattle's always been a cordial, friendly city but folks were less active, less goddamned bushy-tailed in those days," he says.

Eddie puts it all down to a heady mix of prosperity and idealism. "It all changed in the 1970s. Those boys [Bill Gates and Paul Allen of Microsoft, and Howard Schultz, founder of Starbucks], they had so much energy and so much success. It was like the city took in a breath of fresh air and started mainlining fun."

Eddie, like Frasier's father, was a policeman. Now retired, he runs murder tours of Seattle. His speciality is singers: The Gits' Mia Zapata and Nirvana's Kurt Cobain both died here. Eddie was one of the first officers on the scene at Cobain's house in the leafy suburb of Madrona. "That was no suicide. You can't inject yourself with a dose like that and still pull a trigger."

But Uncle Eddie doesn't do so much business these days. Seattle is altogether more wholesome than when he was on the beat and all that energy turns outwards. Add frequent doses of coffee - there is a latte stand on just about every street corner - and you have a city that positively buzzes.

As one of those who enjoys the great indoors - hotel lobbies, second-hand bookshops, wine bars - I'm fascinated by the sheer otherness of Seattle. What is it that makes this a great outdoor city? It's not just the harbour full of watersports, the opportunity to leave work and be parasailing 15 minutes later (yes, Griff has done this); it's the mixture of mindset and climate that makes the place so different. Seattle often has as much rainfall as that other great west-coast resort, Aberystwyth, but when the clouds clear everyone is back out again enjoying themselves. It's latitude plus attitude that makes the place special.

And the city is not so mind-crushingly big that everything seems too difficult. The presence of the water on three sides of this narrow isthmus (Puget Sound, Lake Washington and the ship canal that connects them) means that the city is contained and far from daunting. Besides which there is so much to get out and see. With Griff, and his equally tall and muscular partner, Ashley, we go to all the sights, the markets, mountains and sportswear shops. We watch the seaplanes landing and taking off on Lake Union and we visit the Experience Music Project which is a must for all those who believe that Seattle's third great invention, grunge, deserves its own temple. Personally, I prefer the achievements of Microsoft and Starbucks but I play the part of a good guest.

Eventually, however, I rebel. It's all so active I feel I need some time in the Art Museum with its works by Dürer, Cranach, Rubens and Van Dyke and its Japanese art collection, one of the best in the US. But I am defeated. Closed until 2007. In the end I settle for Uptown Espresso in Queen Anne. It's one of the indie coffee shops and most people agree that it was the inspiration for Café Nervosa. There are wooden tables and old books and I can write postcards while my wife is off watching the kite surfers in Puget Sound with Griff and Ashley's friend Chelsea, who is a deputy district attorney, but looks as if she's just come straight from the squash court.

Dow Lucurell, who founded Uptown in 1985, is as affable as everyone else. "I think at our core we are pioneers," he tells me when I complain of activity overload. "Seattlelites are into the now. This 'sporty' aspect is just our sense of adventure. The bigger Seattle gets the more people want to do things that are active. And hey come on, there are not many places in the world where you have two mountain ranges, the ocean, hundreds of islands, and three large lakes located this close to a large urban centre. It's really why people move here."

British Airways (0870-850 9850; ba.com) offers flights from Heathrow to Seattle from £506. For more information contact the Seattle Convention and Visitors Bureau (020-7978 5233; seeseattle.com)