Suddenly a shout woke us from our fly-swatting lethargy and René quickly headed for the boat, asking us to follow. Running down the path behind us came Heidi, the omelette girl, frantically grabbing at bedding, baby and flip-flops before wading out after us to the canoe.

Heidi settled in the prow, hiding herself and her child under a sheet while on the bank, a man's head could be seen bobbing above the tall reeds as he headed - unaware - back to the village. It emerged that the previous night, this man had beaten Heidi so badly that she was running away back to her mother, a day up river, and we were her knight in shining armour. We chugged away upstream and eventually Heidi and child emerged from under the sheet but they were obviously still terrified and flinched at any movement on the banks.

After a night spent marooned in my mosquito net to escape the vicious biting ants and the biblical proportions of mosquitoes ('muchos bichos'), we set off at six. A few hours later we stopped to allow an obviously ecstatic Heidi, baby under one arm, to run into her mother's arms. To see a girl, barely into her teens, already facing such challenges was chastening, in case I got any big ideas about being a brave adventurer. In return for her safe delivery Heidi returned with a pile of deliciously sweet grapefruit.

Eventually we arrived at the halfway disembarkation point. From here we were on our own and our guide left grinning with most of our funds in his pocket and plenty of fizzy orange for the return journey.

Puerto Cavinas is a place to avoid. It is an army outpost dedicated to patrolling the non-existent river trade and swatting flies. Very few women live there and the staple diet is wild boar. On the map of the Beni and Pando regions that we picked up in Rurrenabaque, Puerto Cavinas was the only place marked between there and Riberalta - almost half the country. After much kerfuffle surrounding our passports, and lunch with the local colonel, during which he expounded the virtue of civil war as an excuse to punish peasants, we tried to escape. Very heated haggling followed and somehow Pablo managed to find the only two mopeds within a 200-mile radius and their drivers so that we could reach the road to catch a bus after all.

Six hours on a moped, weaving precariously along a single track, laden with luggage and occasionally falling off while the driver attempts to navigate in darkness with no headlights is not the best way to see the Bolivian pampas. Or perhaps it is, for despite the miserable journey, the views were spectacular and the landscape of forest, pampas and termite mounds distracted me from the pain in my rear and my driver's vague attempts at flirting.

Arrival at the main road was not as much of a relief as might have been expected. The nearest village to Puerto Cavinas is a lonely place called, somewhat implausibly, Australia. The only hostel is owned by an entrepreneur who also owns the only shop, restaurant, and CB radio, and appeared to be the father of most of the village's children as well. His hostel is a stable with three beds in it, which requires you to take your chances with whoever is already staying in it, and this is mainly lorry drivers. Not a backpacker to be seen. I spent the night with everything of any worth strapped to me and Pablo was so concerned about the other guest assaulting me he didn't sleep at all and got stung by a hornet for good measure. Morning arrived to the sound of speeding lorries and farmyard animals. Without waiting for a bus we jumped on the first lorry that would take us and for the equivalent of £2.50 were whisked away from the stable, its worryingly amorous guest ("I would make a good husband, we would be very happy, you must come with me now" was his opening line) and the only place I have yet been that did not have Coca-Cola.

I never found the soldiers. I ran out of time and money. Riberalta proved quite a test, and a rusting paddle steamer, swarms of mopeds and goat's cheese-flavoured ice-cream laced with typhoid were not enough of an enticement to hang around when we only had £4 left between us and had been living on rice pudding and grapefruit for six days. It is very different from the rest of Bolivia that I saw, as it is heavily influenced by its proximity to Brazil. It even has an air of comparative affluence due to its position as a trading outpost (just what it is trading is a whole other story). Taking the boat was more than worth it but the onion truck from Australia to Riberalta was the last straw.

The 'bootless soldiers' are still out there, as is a story about the US exchange soldiers who practice jungle manoeuvres while their Bolivian peers play with high-tech weaponry in the United States. But it is a story for a braver girl than I. Advance planning would make little difference to the availability of boats, motorbikes or food. If you fancy your chances, I recommend packing a good dose of luck, fluency in Spanish, vast amounts of US dollars and the patience of a saint.