Donkeys in PJs, rats on the menu and France's Venice - only it's green. No wonder we feel like we've slipped through some sort of portal.

But let's back up a little. We've been travelling for weeks in France and finally after a surfeit of fields and mountains, we are off to the beach - or more precisely the Ile de Ré.

Fields of sunflowers and wheat flank the road on the way to La Rochelle, the city that now anchors the island to the mainland. From a distance, the three kilometre long Pont-Viaduc appears hardly more than a gently arching causeway, yet its opening in 1988 caused controversy. The toll to use it seems steep enough too, but then we see a notice announcing it is just days until the summer increase takes effect. It will then almost double in cost.

Of the few villages on the island, St Martin-de-Ré seems to be everyone's pick - and, in July 2008, the town's citadel, was added to UNESCO's list of World Heritage sites. There are thirteen groups of fortified buildings and sites, including the Saint-Martin de Ré ramparts, representing the finest examples of the work of Vauban, a military engineer of King Louis XIV. It is the quintessential island town with a fishing harbour ringed by restaurants and a laid-back feel that has been earned honestly. We stay for some time, soaking up the sunshine and the atmosphere before pushing on.

Nearby an unexpected welcoming committee is waiting. I have read about the large donkeys, the baudet du Poitou which stand almost as high as a horse, so we are thrilled to find several in a field just outside the town walls. They are friendly and inquisitive. They are rare too. It is estimated there might only be around 400 in the world but they have been popular on this island for many years. Their shaggy chocolate brown coat gives them an almost comical dread-locked appearance, and with their white muzzles and chunky build, they resemble a child's giant overstuffed toy.

Sadly we miss seeing them in their PJs - a sight which has become a sort of unofficial emblem of Ile de Ré. The salt marshes are of prime importance on the island and the farmers some time ago came up with the idea of putting trousers on the donkeys to give them some protection from the mosquitoes and corrosive salt.

La Flotte, the island's Les Plus Beaux Villages representative, reminds us of a Cornish fishing village and its restaurants, elbow to elbow around the keyhole marina feature seafood of course. Blackboard signs placed strategically on the footpaths so tourists nearly trip over them offer tempting suggestions: hu'tres, crustac's, poissons, moules & frites - volonté! (as much as you want) or plateau de fruits de mer - emporter. That's oysters, seafood, fish, mussels and a seafood platter.

No doubt it's all fresh this morning from the fishing boats now lazing in the water a few steps away. This island is a favourite family holiday destination for many French people and we pass bright and inviting holiday homes along the esplanade as we stroll towards the marina. A takeaway (- emporter) seafood platter seems a winning sales idea to me. What could be better than to sit on your own (well, your own rented) terrace with a view of the bay and a selection of the best seafood of the day washed down by a crisp local white?

Bright colours are popular on this island. Most homes are whitewashed to a dazzling uniformity, accented only by royal blue or deep green window shutters, while spikes of tall pink hollyhocks stand out starkly against the walls. Sometimes referred to as the 'white island' Ile de Ré earns this name on several counts. Most noticeable are the chalky cliffs and sand dunes, and those blindingly white houses, but as well, the far end of the island is known for its salt beds.

Loix is one of the centres for the salt industry. The local citizens seem to have an artistic streak too, and we drive around the back streets, admiring murals on many house and garden walls. One depicts a farmer with his pitchfork and dog beside a Poitou donkey staring out moodily above the (real) hollyhocks planted at its feet. Another, almost lost in the shrubbery, has been portrayed wearing its blue checked pyjamas.

Moving inland and north again, we head for the Marais de Poitevin - La Venise Verte or Green Venice. We soon launch into a waterlogged land where mossy paths turn out to be rivulets covered with fine emerald green algae-scum. Tiny wooden bridges span shining 'roads' overhung by trees, and occasionally we confront creamy cows, who stop chewing, surprised, just long enough to ponder our appearance. 

And while the waterways seem narrow and scaled down, the area is extensive: eighty thousand hectares of marsh (marais) some of it drained, and dotted with villages and forests, an eco-paradise for both the visitors and the many species of birds it attracts. Who knows how many kilometres of canals there are. 

We become lost almost immediately.

For those with time, the obvious solution is to hire a barque, a form of punt, from an 'embarcad're', or take a bicycle and devote several hours - maybe days - to losing and finding yourself again among the complicated network of canals, waterways, roads and lanes. It becomes fun once we adopt that mindset too, and allow ourselves to wander, almost unsure whether we are on land or water as the two apparently merge and interchange.

In some villages which are more tuned to tourism, rows of low black rowboats with yellow plastic seats stand waiting for customers. While some people gently row themselves off for a day of relaxation, other boats provide someone to do the work, the oarsman standing like a gondolier at the front, poling the group along.

At Coulon, the main centre for the Marais, we realise we should eat soon before it is too late to find a restaurant open. It is Sunday, the day in France when lunch is a relaxed and lengthy meal. The water's edge it has to be, of course, but the restaurants are packed, doing a roaring trade in lunch and boat tour packages. Little wonder as the weather is showing off the Marais at its loveliest and you'd be mad not to want to dine outside by the canal. Finally we find one empty table for two in the corner of a terrace, right beside the footpath.

As we approach the waiter, he begins to shake his head until I point it out, and he nods. We're in! What's more the blackboard offers a generously priced Menu du Terroir (regional food menu). There is local ham, and fresh Atlantic-caught fish, a plate of regional chevre with salad, and a terrine of myocastor. I query this last one, but the waiter shrugs and makes 'small-animal' running movements with his hands. I ask if it might be rabbit, and he shrugs.

It is delicious and it is only much later that I discover I have consumed coypu, a small rodent! It lives in marshy areas (so it is certainly regional here!) and looks like a water rat. Too much like a rat, I decide when Google helpfully directs me to a photograph.

I have a Fawlty Towers flashback, channelling Manuel. "Eees haaam-ster!"

Right now, mercifully oblivious to what I have just eaten, we take the scenic route away from the Marais, dilly-dallying beside canals flanked by cottages which could have been lifted from some catalogue of 'France's prettiest houses'. We admit at last to a surfeit of sunburned tourists rowing in unison, endless regiments of hollyhocks, and quaint blue-shuttered whitewashed houses with flat bottomed boats at their front doorsteps, narcissistically admiring their perfect green reflections. 

As we head north, the portal closes gently on donkeys and water rats, and this sunny corner of France.