A dugout canoe enables you to penetrate into the narrower channels. If you are lucky, someone else will do the paddling - it's surprisingly hard work!
My canoe trip was curtailed by bad weather, but not before I had seen a turtle, capuchin monkeys and a huge blue butterfly.
You travel along the main in a fast motorboat, but your guide will stop the boat when there is something of interest to see. It's a good idea to wear sunglasses, even if it's a bit overcast, so that they can double as goggles. Beware: if it rains, it will really sting whilst you are travelling at speed. We were given a plastic sheet to hold up to keep the rain off - but ended up semi-suffocated by wet plastic sheet. When it gets too unpleasant, they stop the boat until the weather eases.
In the side channels, the boats travel at a much more sedate pace.
We saw pink river dolphins, red howler monkeys, parrots, toucans and a host of other birds and plants.
I had been a bit nervous about the promised piranha fishing expedition, having read stories about people wading into the water with the piranhas.
It was not like that at all. We were taken in a boat to a nice, quiet backwater, given a rod (well, long stick) with a nylon line and twisted wire hook and a piece of meat as bait.
The technique is to beat the end of the rod on the surface of the water a few times before dropping the hook and bait in, and wait until you feel something nibbling at the bait. If you're not quick enough, you will find an empty hook, with all the bait gone. (It is rather more like feeding the piranhas than catching them.)
If you are lucky enough to catch any and take them back to your camp, the staff will cook them for you. I managed to catch one fairly small and embarrassed looking piranha, whilst my other half managed to catch a submerged log and break his stick (er, fishing rod).
Piranhas are quite tasty, but there is very little flesh on them.
A walk in the jungle enables you to see some of the plants up close. Your guide may even give you an opportunity to taste some of them.
Be careful - the ground is very muddy and slippery. Your lodge will supply wellies. Make sure that you also have plenty of insect repellent (with a high % of DEET), and are wearing long trousers and a top with long sleeves and (ideally) a high neckline.