Legs Cycling in Australia

In the Northern Territory the heat is just as surprising as your first wild koala sighting - you know it's going to come sometime, though it's still startling when it does. But breaking camp and cycling off as the rim of the sun glowers on the edge of the earth is a chilly moment as the freewheeling breeze washes away the night's clamminess. The clear air is tainted with dust thrown up by the tyres; you can smell it before you see it. This is a hungry moment, but breakfast can wait until things warm up enough to make a halt essential. Last night's leftover tea from a water bottle - shockingly cold as it swills over your teeth - will do for now.

In cycling terms, this is as good as it gets out in the bush, a combination of perfect temperature and physical freshness which lasts an hour, maybe two. Everything feels right: your senses are sharp, your legs strong, the wheels turn smoothly and the bike feels like the amazingly efficient machine that it is, more fluid than mechanical, integrating perfectly with the easy motion of the body that drives the pedals around. That early morning sense of potential - eating up the miles measured on the map in thumb-lengths last night by the campfire - has yet to be shattered by heat and fatigue, and worst of all, a lack of water.

And it's water that is the ultimate objective: Litchfield national park is all about this precious element. Litchfield has an abundant supply rising from deep in the ground, in the middle of thousands of arid square miles, which feeds rivers, water holes and even tiny pockets of monsoon rainforest, buzzing and crawling with life. Timing your visit in this area is vital: the wet season, from November to March, is impressive but impractical, so the relative cool and dry of June is a better bet. The driest and hottest time, from August until the return of the rains, gives the greatest concentration of animal and bird life at the few billabongs which haven't dried up completely.

Getting to these pockets of water is half the fun, or at least, half the experience. If the breaking day is full of the best bits - the last stars, the sounds of the bush coming alive, a sub- tropical zany mixture of bird, insect and marsupial clatter. Then the growing, smothering heat and the endless miles reveal the true nature of the land, the bit you miss from a plane or even from an air-conditioned four-wheel drive. You are light years from the Opera House or any sign of a surfboard and as close as you can get to the essence of the country, its space and scale.

Surviving the ride is a combination of a rhythmic, pedalling-induced trance punctuated by breathtaking flashes of life: high-speed flocks of azure budgerigars, brilliant against the grey-greens, dusty whites and reds of the gum trees, or swooping cockatoos. More frequently it's a deep patch of dust which wrenches your handlebars and you back to reality: thudding heat, perhaps the smell of rotting 'roo from a roadside corpse, niggling preoccupations of where to find water and whether this is really the right track. On more major, tarred roads, the surprises come from aptly named road trains - multi-trailered trucks - hauling livestock at high speed, and giving way to no one. Cycling in the cool hours of darkness, the only risk comes from colliding with cattle and just occasionally kangaroos which have taken to the warmth of the tarmac for the night.

The bush has a rhythm, too: layer upon layer of exfoliating eucalyptus manage to look drier than the dust from which they grow, yet they shelter all kinds of life, including the scary stuff such as red-back spiders and any number of poisonous snakes. In practice you would be lucky to see any of it, but you certainly hear something, rustling under the groundsheet of the tent at night. Almost as rare, the farther you get from a town, is contact with aborigines other than those employed as park rangers, though certain areas abound with astonishing rock paintings which teach the aboriginal "law", or code for living, based on their creation story, the Dreamtime.

Before you reach your goal, a forest of 10ft-high termite mounds leaves you gasping, and then the forest canopy thickens and you hear the sound of Florence Falls, which even my over-cooked brain can interpret, goading legs that can barely turn the pedals. Not only can you drink the water, but there's enough to swim in and it's croc-free: you don't need to be asked twice. It crashes down the sandstone cliff on to you, sucking the heat and the sun's rays out of your skull, partially restoring your senses. Suddenly you realise this is an oasis not just for swooping fruit bats, lizards the size of small dragons and screeching birdlife but for cyclists too, for whom it has suddenly become all worthwhile. Eric Kendall

Access www.atn.com.au/ for general planning, but don't expect any specific cycling information. The extreme north of the Northern Territory is accessible from Darwin, which has an international airport.