Watching wildlife is often the outcome of random encounters, and your luck never seems proportional to the time and effort you put in. Sometimes you lie silently on your belly on a freezing moor at dawn for hours and don't see so much as a rabbit, but at other times, you stroll along whistling and almost trip over a rare and wonderful animal. We were quite fortunate on this trip and had a lot of the latter kinds of experiences, including seeing not one, but two, whole anacondas.
Let's get one thing straight from the start: it's not like in the film. They don't suddenly lunge up out of the water and consume a boat and its occupants. They are fairly shy, and tend to lay low, quietly suffocating and swallowing smallish animals in private and out of the gaze of curious tourists. They also don't need to eat very often, so catching them in the act is even less likely.
We saw anaconda 1 on a horse ride. We were gaily wandering through a shallow lake on horseback, when one of the guides jumped off his horse, and started excitedly poking about in the rushes. He'd seen an anaconda which was in the process of constricting around a caiman and eating it. You might think that jumping into the water next to a snake big enough to swallow a medium sized caiman is a bad idea, but doing so while it's feeding on a medium sized caiman is probably as good a time as any, because the snake is actually rather busy. That was exciting.
The location of anaconda 2 was given away by some jacanas (big-footed water birds, similar to coots or moorhens). They were going crazy with alarm calls, hovering over a particular patch of water and looking very nervous indeed. When we looked through the weeds at the spot they were troubled by, we saw a lithe, yellow, spotted body slipping through the water. We were out of the water this time on a bridge, but one of the guides -- in his enthusiasm to show people wildlife at as close quarters as possible (with just a touch of wanting to impress the laydees) -- waded carefully in and grabbed the snake's head, hauling all 2.5 m of it out on to the bridge for us to hold.
I really prefer it when people leave wild animals alone, even if that means you don't get such a good view. Better a brief glimpse of a wild animal behaving naturally than a long look at one which would really like to go and hide in the water, thank you very much. However, there are times when you can't get a real impression of the physicality of an animal without seeing it up close and touching it. The warm, dry skin of the snake was beautiful, and the incredible smooth power of its muscles as it gripped our hands and arms was something that just looking at it wouldn't have conveyed. The guy put it back in the water gently, then backed away carefully. They may not rear up out of the water to attack you, but they do command a certain respect.