Oyapock is an Amerindian name and one that is redolent of adventure. It well suits this account of the journey up the river where everything changed the moment we passed the Saut Maripa.

But let’s start at the beginning. My first night, in a hammock, was spent at Chacara do Rona, in Oiapoque on the Brazilian side. The caipirinas that evening whetted my appetite for discovery, and the following morning I naturally found myself lugging baggage up over the Saut Maripa. This is not the biggest sault in French Guiana but it is certainly the widest and most beautiful. We set off – I say ‘we’ as I was travelling with other people who were also looking for virgin territory – in a big pirogue expertly handled by Pedro.

From the outset it is a thrilling voyage with a series of saults and steep rocky slopes whose names sounded strangely familiar to my ears: Kachiri, Pakou Akara, Waïwarou, Grand Keïmou, and so many others that add to the grandiose landscape.

The bows of our craft cut through the waves of the rapids as we shrieked with joy or fear before finding the safety of calmer waters further upstream. The water level was very low as it was November, and on two occasions we had to get out to let the pirogue navigate some tricky places. We took advantage of this to have a swim. If the truth be told it was extremely hot and suncream and sunhats were essential.

Our first real halt for lunch was on a sandy islet in the transparent water of the Anotaï creek. A paradise of calm. We set off again accompanied by the chugging of the outboard. Like the other passengers I dozed off now and then, but I still enjoyed the landscape slipping past on either side.

After several hours we caught sight of the first dwellings dotted about in the vegetation with its many shades of green. At first they seemed rather incongruous but they ended up becoming more fully part of the landscape. Finally we arrived in Vila Brasil, a Brazilian town opposite Camopi. We spent a calm evening there full of languid discussions and contemplative silences, drinking in the brilliant light of the full moon illuminating the landscape.

When I awoke the picture before my eyes seemed unreal, as the fog was so thick over the river. It formed a vast layer of cotton wall muffling the sounds of life stirring all around. I was so caught up in what I could see that I was surprised when suddenly the mist broke and I could admire the purity of the light here at this time of day.

But we had to set off and continue our visit. This first took us to an area where the trees had been felled, and then into the primal* forest where our guide showed us the species used for their fruits or medicinal qualities. Everybody assailed him with the good-humoured questions.

Our time was spent talking, swimming, discovering places and their inhabitants, and especially the Amerindian population. There are two native communities living in this region, the Emerillons and the Wayampis. Some of them sometimes come in to Vila Brasil to buy things, which is a first step in contact even if there is no real exchange. Their simple calimbés, a simple strip of red fabric worn between their legs, contrast with the colourful football shorts and shirts of their Brazilian neighbours.

But it was time to think about heading back. We started our descent, stopping off to visit an inselberg and for a picnic on the Montabo creek with its crystal-clear water. In the evening, sitting on the terrace at Chacara do Rona with the final caipirina, our minds were still back upstream.

It is a four-day trip and truly is a voyage of discovery, enlivened by the time spent together during which all the members of the group were keen to get to know each other and the places.