Swimming with the dolphins
When we cruised down the river for three hours yesterday, we saw quite a few of the famous pink dolphins of the pampas. This afternoon, we didn't just see them: we jumped in the water, and tried to swim with them. Unfortunately, the dolphins are both shy and speedy: as soon as you see them in one spot, by the time you've swum towards them, they've already popped up somewhere entirely different. I think they like to taunt as well. But hey, it was good fun sharing the river with them.
Some people in other groups reported brushing against the dolphins in the water, and even getting lightly bitten by them. Sadly, nobody in our group was able to achieve these great pinnacles of glory. However, Matt and Dave made a damn commendable effort at it. They were in the water for way longer than the rest of us, swimming around, treading water, and trying to get as close as they could to our aquatic friends. But to no avail: even the surfer Aussies couldn't manage it.