"¡Mire! Hay delphines allí", I said to the village girl standing next to me. She was about nine or ten. Every time she looked at the river there was nothing, and every time she looked at me with a look of puzzlement another couple of dolphins would leap out of the water behind her - "¡Mire, Mire!" Eventually she saw them and was jumping with joy.

These were grey river dolphins. I'm sure they toy with us, as did the pink river dolphins that I saw from a small boat on which I took a jungle tour with four Germans. The pink dolphins were an amazing sight, but impossible to capture on camera. In the lagoon where we found them our guide told us that it was a safe place to swim - no piranha fish here, no anacondas, and none of those horrible little fish that swim up into your bladder. So in we jumped, just as the pink dolphins started to leap out of the water and perform all kinds of acrobatics, knowing full well that we couldn't reach our cameras!

Another fascinating wildlife sighting from the river was the giant sloths which we saw climbing trees at dusk. And in the jungle, where we slept in hammocks for one night, we saw monkeys, macaws, a snake, tarantula spiders and some huge insects - all of which seem to want to bite you! Fascinating, but scary! It rained heavily whilst we slept under the mosquito nets, and we found it hard to wade our way back to the river in the morning - I was glad of the wellies that had been provided, but the water was over the top of them at times.

The flooding also made for an interesting border crossing. On arrival on Santa Rosa Island in Peru, only two of us got off the boat to look for the customs post. There was too much water to get into the village, so we had to take a small boat which took us first to the door of the customs man, and then through the village streets to immigration to get the passports stamped. The boat then took us across the river to Leticia in Colombia where a walk to the airport was necessary to get the passports stamped again. Generally the borders here are very relaxed, and I have also briefly visited Brazil, where the village of Benjamin Constant is just across a small river from Islandia in Peru - the people can wave to each other from their houses, but they speak different languages, and won't accept each others' money.

From Leticia it is possible to hitch-hike north along a new road, which is under construction; and then join the river system through Colombia to eventually emerge on a road to Bogotá. But this could take weeks, so I am very reluctantly taking a flight out of here to save time, and in fact money too! It's a real pity to have to do this having come pretty much all the way from Cape Horn overland (and water), but at least I should get an aerial view of the huge rainforest, which I have said little about...

It's big! Look at any world map, and you can see that it's big, but when you spend three weeks getting here, and then look at a map to see how far you have come, then you really start to appreciate how big it is. It takes one month more to continue down river from Iquitos to the Atlantic Ocean. And away from the river, there could be anything out there that we still haven't discovered. I was sceptical that there could still be people living out there that have not yet come into contact with modern humans, but now I can see that this is still likely, and only recently a helicopter flew over a tribe that had had no contact with the outside world until it flew over them and took their picture.