YESTERDAY at the Edinburgh International Book Festival, Kirsty Gunn's The Boy And The Sea was announced the overall winner of this year's Sundial Scottish Arts CouncilBookOfTheYearawards.Few would suggest that she didn't deserve it - John Burnside, who won in the non-fiction category for his memoir A Lie About My Father, spoke for everyone who has read it when he said that The Boy And The Sea made him feel "like a teenager again" when it was first published last year.

Like her three previous novels, and many of the stories in her 1999 collection The Place You Return To Is Home, the principal characters are not yet adults, and are subject to a youthful mutability of emotion that Gunn seems dedicated to mastering in prose. "I do have a lot of adolescence in my books," she says.

"There's something about that changeability, that being on the cusp. These themes do recur. They go round in your head like music."

She is not entirely certain - Gunn's attitude to her body of work seems slightly inflected by the same sense of the "unknowable" that draws her to write about bodies of water - but thinks this most recent novel may be a companion piece to her debut, Rain (1994), which was also concerned with a boy's inner life, and his relationship to his environment.

Neither book, nor any of her other fictions, have been set in any specific place. Rather, they are located in elemental topographies that suggest features of her birthplace, New Zealand, as well her ancestral and adopted home of Scotland, and imaginary spaces in between. (Gunn and her family divide their "incredibly complicated life" between flats in London and Edinburgh, her husband David Graham directing Granta Books and its magazine while she teaches creative writing at Dundee University.) "I think it's beautiful," she says, "that you would use the word elemental', because I have always tried to use the places in my books not simply as a setting but almost as a character, and Scotland is a huge part of my imaginative landscape. It's true that I've never been explicit about it, and some people don't like that.

"Not long ago, actually, a journalist came up to me in a cocktail bar in Edinburgh and said she really liked my writing, but it pissed her off that I never name the places."

The events described in The Boy And The Sea - which is set among teenage surfers on one hot day in the summertime, as a young man called Ward reflects on his feelings about his best friend and his father - could theoretically happen in Scotland. There are, as Gunn points out, small communities of surfers who do congregate our north and west coasts, where hot days and the Americanised usage of the word "awesome" are rare but not unheard of.

This book in particular, though, Gunn did not want to be rooted or earthed. There is an essay in her recent assortment of short memoir pieces, 44 Things, which describes the appeal of the sea as infinitely larger and more ambiguous a metaphor thananythingfoundinlandlockedfictions: "What happens to boys when they go into her, the water? The sea speaking, feeling, having her own story "

There are also essays in 44 Things which celebrate the "domestic" and "quiet" in literature as no less substantial than all the action that propels most of the classics in the canon. More important to Gunn than events in themselves, is the "sound and colour and shape" of each word. "It is unbelievably time-consuming," she says, "because as William Carlos Williams put it in his wonderful phrase, How can I know what I mean until I see what I say?' I'm striving for a kind of music, and I will go through something like 14 drafts. I'm not making any claims to poetry but I am in awe of poets who work and work and work to get that absolute sense of finish, I think is the word."

That word also implies that Gunn's published works are as close as she can get to perfection on her own terms. "Well, I don't take much editing. I am quite fond of ellipses, though." ("Well," says Ward in The Boy And The Sea, "I had a swim. I guess ". Many other sentences end in the same way.) "We decided that quite a few dots had to come out of this book," she says.

Gunn is not immodest. When asked about yesterday's award (she received £5000 for winning in the fiction category, and £20,000 for winning the best book overall), she says she is "hugely honoured to stand alongside John Burnside and Maggie Ferguson whose biography of George Mackay Brown was voted best first book of the year, writers I hold in the highest esteem."

She goes on, however, to sound a little like John Banville, whose gratitude at winning the Man Booker prize in 2005 for his not entirely dissimilar novel The Sea was tempered by his congratulation of the judges for recognising literature when they read it. When reminded that Scotland is a country that does not always or consistently give its best writers pride of place, or even a seat at the table - Gunn has argued in this newspaper that James Kelman is "the greatest British novelist of our time", although the man barely makes a living wage - she agrees that "literary fiction in general doesn't get enough attention".

"The middlebrow has become predominant, and the bookshops are full of Jamie Oliver, while mighty writers like James Kelman are almost ignored. All we can do is keep reading him. But I do think it shows the amazing intelligence and breadth and reach of this judging panel that it has embraced this short novel of mine that is in so many ways such an unconventional piece of literary fiction. I'm grateful because it's so very encouraging ... "

The Boy And The Sea is published by Faber, £6.99. 44 Things: A Year Of Life At Home is published by Grove Atlantic, £15.99