I have been meaning to contact you and Richard since I got back from Bolivia to let you know about the giant anaconda stories that Richard asked me to look into.
I asked around and although I didn't see any anacondas myself, the locals said that they were about and that they usually grow to around six to seven metres in the area that we were in. Of course there are stories of huge snakes but no one had seen any personally. We also checked out a small cave where anacondas were supposed to be present but found no signs. I managed to crawl to the end of the cave and found no snakes of any sort but the cave did continue and I could see openings further on but with my head touching the ceiling and my chin scraping on the ground and the water level just below by nose, I thought that it was time to turn back. There was no way that I could've gone on any further anyway as the opening was about the size of a basket ball. The cave was full of bats (unsure of the species) and the locals did say that during the rainy season (which should be about now) that giant bats (possibly vampire bats) inhabit the caves. These bats were supposed to have wing spans of up to a metre. I don't know if this is possible or not but the locals seem convinced that it is so. The locals were also very nervous of this cave. One of our guides would not leave the mouth of the cave and made sure that he had a machette in his hands the whole time we were exploring this cave.
So, unfortunately no sign of any giant anacondas on this trip.