Walks around the world: A river runs through it

Weekend walk: Jonathan Stebbings treks downstream to the heart of Exmoor

This seven-mile walk follows part of the Two Moors Way in the heart of Exmoor. It has two distinct halves: initially following the river Barle through the sheltering beech woods and meadows that line its banks from Withypool to Tarr Steps - then up to Withypool Hill, to be exposed to the bracing winds and views of the great moor. The walk offers a hearty elevenses or tea half-way round at Tarr Steps, and finishes with a pint of Exmoor Ale and lunch or dinner at the 17th-century Royal Oak pub in Withypool, so it makes an ideal morning or afternoon stroll.

Start at the Royal Oak in Withypool, leaving the village on the Winsford road to the east; 500 yards up the hill, climb the stile on the right. The path winds through Uppington Plantation, below Uppington House, leading you gradually down to the river. About half a mile downstream you pass the stepping-stones across the river to South Hill.

The river here is shallow, and much of the year rocks or tree trunks break the surface, creating the bubble-filled eddies that make perfect hunting-grounds for dippers. These dapper little birds, sober-suited wrens with white breasts, flit low along the river as you drive them downstream. Keep an eye on the branches above the water for kingfishers.

The wood eventually opens into a flat area of meadow, with Bradley Hams rising steeply behind. On the opposite side, Hayes Wood looms above, the tree tops bearing the great nests of a large heronry. During the nesting season the herons flutter on the breeze carrying building materials or food with the grace of a second-row forward playing hopscotch. As both banks become clear of trees, a ford and a bridge cross the river to Batsford Farm. Continue on the east bank.

From this point the river meanders more erratically, the sides of the valley get steeper and the woods close in. The path is easy to follow, allowing you to relax among the shadows and birdsong. The river becomes more voluble as its speed increases with the gradient. Badger and red deer roam the woods, which are full of bluebells at this time of year.

Four miles downstream from Withypool, the river widens and the shallows are crossed by three steel hawsers. This is not an adventure training exercise but a device to catch the tree trunks that are brought downstream when the river is in spate and threaten the even more extraordinary structure below. A hundred yards further on the broad shallows are spanned by a series of massive flat boulders (the largest is 10ft long and weighs two tons) lying across equally massive stone piers. The edifice looks as if it should be guarded by a troll to match its scale - it is 180ft, including the surface stones on the west side.

Tarr Steps have been the victim of legends attributing them to giants and the devil - you immediately imagine they are of an age with Stonehenge and Avebury, but the likelihood is that they are a medieval construction to allow drovers to get across the river without their sheep getting soggy, like the clapper bridges of Dartmoor.

To get a good view of the steps you can cross the river through the ford without its going over the top of your boots most of the year, although you may be caught by the wake of a passing car.

Salmon can be seen in the upper pool during their autumn runs, while otters and, increasingly, feral mink may be seen scurrying on the bank or gliding through the water in pursuit.

Sustenance can be found on the east side, at the 16th-century Tarr Farm, which serves wholesome cakes, cream teas and full meals, either in its warm, timbered interior or in the garden, which looks down to the steps and up the hill to a couple of large and frisky black stallions.

The return leg begins by crossing the river and continuing along the Hawkridge road for 50 yards, before taking the lane up the hill and the Tarr Steps Hotel. The lane becomes quite steep, passing the hotel on the left, and is bound by high, moss-covered banks. After 300 yards the lane turns sharply to the right, and then peters out at the junction of some worn-out hedges high above the valley.

Follow the hedge line due east across fields for half a mile, away from the river. You will pass the brow of the hill on your right as the slope takes you down towards Parsonage Farm. Before the farm gate, follow the footpath sign to the right; this will take you round the north edge of Parsonage Down to Westwater Farm a mile away.

At Westwater you join the lane from Hawkridge to Withypool. The walk home is one-and-a-half miles, with the river threading its way through the woods down to the right and the moor rising to the left. It is worth leaving the road to climb to the top of Withypool Hill. There is a small tumulus at the top and a stone circle 200 yards to the south west. At 398 metres, the hill offers fine views over the moor, especially Winsford Hill two-and-a-half miles to the east, and Dunkery Beacon five-and-a-half miles to the north east, at 519 metres the highest point on Exmoor. On entering Withypool you go over a cattle grid and cross the river again over a delightful, six-arched bridge. The road leads up through the village to the Royal Oak.

Length: seven miles of generally easy walking, with one steep ascent. Time taken: one-and-a-half hours to Tarr Steps and one-and-a-half hours back at a leisurely pace. Ordnance Survey maps: Landranger 181, Outdoor Leisure 9. Royal Oak, Withypool 01643 831506. Tarr Farm, Tarr Steps 01643 851507.