THE SUNDAY WALK: John Shearlaw traces a route through the strange and haunting landscape of the Somerset wetlands
In the dark, freezing nights of early November, the summer visitors are gone from Somerset - yet the lanes are full to bursting once more. Because for local people, this is the start of the real holiday revels when giant 100-foot-long Carnival displays parade the streets from Bridgwater to Glastonbury and fireworks and bonfires light up the skies.

Tomorrow the two-week season continues at Burnham-on-Sea, and as a prelude to the night's hectic entertainment here is a daytime walk of wild and inspiring solitude. It starts at Combwich, an old Roman sea port. Glastonbury pilgrims passed this way for centuries, fording the river Parrett mouth on a shelf of blue lias just south of the modern wharf.

The Parrett boasts the world's second highest tide range and now a trail for walkers has been marked out from its source in the low hills of Dorset to Bridgwater Bay, an English Nature national reserve. Winter birds arrive here in November; all around the Bay vast numbers of waders and wildfowl probe the silt for crustaceans, worms and snails.

Pick up the trail signs at Riverside Road in Combwich, passing the Anchor Inn before hitting a track along the high west river bank. From a once thriving fishing fleet, only one man, Brendan Sellick, still fishes these treacherous mud reaches, using an ingenious rope-hauled wooden sledge. The fruits of his labours are on sale at Stelford Fish, just down the coast.

A mile along the bank high and low paths converge. At the next gate, turn left down the bank onto a marked track, traversing the drained flatland for a mile until a metalled road at Bowells Farm.

Cross over and walk through the English Nature car park to reach the shingle bank which will lead you round to the head of the estuary.

The signs warn of fast-rising tides and stray shells (the Bay was used as a Second World War range), soon forgotten in a seemingly endless wilderness of mudflat, sea and sky. In an east wind, for a human, Steart Island can be the coldest, loneliest place on Earth.

Yet a mile across the water lies the proudly preserved Victorian frontage of Burnham-on-Sea, complete with pier. Behind it, the ghastly drumlin of Brent Knoll. Continue along the estuary to ascend the steps of the mighty 30-foot new clapboard bird tower. From here a strange and haunting landscape lies before you.

The low-lying Steart and Fenning islands, the Parrett's final line of defence against the Bristol Channel, are an internationally important wetland.

Bring binoculars for a vigil, or marvel at the patience of the "twitchers" who have added their sightings to the hide's rapidly filling log. "10,000 black-headed gulls, arriving at the rate of 600 per 10 minutes" notes one. 'Two common scoter, attacked by peregrine. V. windy, tower shaking"notes another more ominously.

Other hides cling to shingle banks where the channel widens, havens as a brilliant winter light bounces across the silt and the sea. On Stert Flats in sunshine, light shimmers like nowhere else.

The return path heads over a stile, leading towards the first of Steart's farmhouses, built with its back to the sea. Defences have been established here since the 12th Century. After a near-disastrous flood in 1981, the walls were raised another half metre.

Continue to the metalled road, the car park a half mile away. Turn left at Dowells Farm to retrace your route to Combwich. "Di welcomes all" proclaims the sign outside the 16th-Century inn the Old Ship Aground. Parrett Trail finishers celebrate here, with '"warmers" available all day by a roaring log fire.

A few hours later, while thousands of us enjoy the heat and bustle of the Carnival, the tide will again reclaim the mudflats. And the durlins, the godwits and the shearwaters, Somerset's other winter locals, will carry on reclaiming their home.

Burnham and Highbridge Carnival takes place on 10 November, starting at 7pm. There will also be a firework display on the Esplanade tonight, again at at 7pm. Other Somerset Carnival processions follow at Glastonbury, Wells and Shepton Mallet.

The walk area is covered by the excellent Ornance Survey 1:25000 map Explorer 22, the Quantock Hills and Bridgwater.