Books: Why it's a good idea to keep your trunks on

Waterlog by Roger Dakin Chatto pounds 15.99

A t the 1997 World Championships in Australia, swimmer Steve Zellen lost his trunks as he dived in at the start of a race. He swam on but was disqualified. "Arguing his case before the judges," continues Roger Deakin, "he said he would have stopped had it been a backstroke event." This is just one of the myriad anecdotes, both ancient and modern, that enliven his account of swimming the length and breadth of Britain. His role model is Ned Merrill, the John Cheever character who, in a short story called "The Swimmer" (later filmed with Burt Lancaster), decides to swim the eight miles home from a party via the pools of his Long Island neighbours.

And so in the spring of 1997, "feeling sad at the end of a long love", and with his son having fun, fun, fun Down Under, Deakin sets off from his moated Suffolk farmhouse for the Scilly Isles. Over the next 18 months he swims across beautiful bays, fords deep rivers, splashes about in chuckling streams and even descends into Hell Gill near Ingleton in Yorkshire: "an experience somewhere between potholing, swimming, surfing and rock-climbing". Deakin claims to be "just an ordinary man-in-the-pool swimmer of no more than average ability" but he clearly possesses uncommon stamina. He favours the breaststroke and black Speedos. When the water is very cold, which seems to be most of the time, he wears a Bibendum wetsuit. However, he is not averse to a bit of skinny- dipping. The very word, with its four short vowel sounds, mimics someone tip-toeing into icy water.

Deakin is aware that public bathing, like a David Hockney swimming pool, is both "erotic and innocent at the same time". He doesn't like naturists though. At Holkham in Norfolk, the sight of "The Unclothed Ones" popping up and down in the dunes reminds him of "a scene from Watership Down". At Porthcurno in Cornwall, he finds "something subtly aggressive" about their nakedness. Isn't that what head-doctors call transference? Whatever, the determination of some folk to frolic in their birthday suits is, given our climate, not only brave but peculiarly British.

Deakin has evidently immersed himself in local history and natatorial lore as well as the Leeds and Liverpool Canal. Here, too, eccentricity abounds. Members of the Houghton Fishing Club were reminded that no angler could "fish before the 1st January nor after 31st December in any year - Leap Year not excepted." In 1924, for a bet, 15-year-old Sonny Goodson dived from the roof of the Norwich Art School into the River Wensum - a horizontal distance of 40 feet. His reward? pounds 1 2s 4d.

As its title suggests, Waterlog is as much about writing as wallowing. Deakin may have travelled widely, but he has read widely too. Page 95, for example, contains references to Enid Blyton, Thoreau, Courbet, Henry Moore and William Morris. His use of dialect words for dykes, mud banks and suchlike - roddons, croyes, glidders and uvvers - creates another sort of water music. However, it is his love of nature that impresses most. A film-maker by profession, he reveals an eye for colour: the waters he swims through are peat-brown, mud-green, turquoise, silver and black. He makes you feel "the curious half-ticklish sensation of damp, corrugated sand" in the arches of your feet.

A run-in with a couple of water bailiffs - "straight out of Dickens" - at Winchester College highlights the issue of access to riverbanks. Pollution is a bigger problem. The Environment Agency, which Deakin finds unhelpful and patronising, protects our waterways by discouraging swimming and spreading scare stories about sewage and Weil's disease, "a potential killer" found in the urine of rats. Nevertheless Deakin manages to convince you "there are still some places left in England that have unquestioned magic about them." Although he does not provide a bibliography (or maps), Deakin does acknowledge the mighty influence of Charles Sprawson's hymn to swimming, Haunts of the Black Masseur. The Cheever story has little relevance apart from its title: it is a tale of physical and mental breakdown. Merrill reaches the point of no return; Deakin never even gets into difficulties. Most travel writing is a form of autobiography, a journey into a personality as well as a place. Deakin is no Narcissus: he gazes at the water yet reveals little of himself except a few childhood memories. He remains a stranger. Consequently, Waterlog is all surface, always a joy to skim but without any real depth. This is a pity because even the slightest hint of self-discovery would have made this very good book a great one.