One of the two main tributaries of the Amazon (where they meet is where the Amazon name starts). The river is basically like a highway: it is not dank and jungle-ish like we see in the movies. It is open, wide, and used like a highway. It can also be very shallow, and because it is silty, it can be very hard to find the channel. Our boat bumped the bottom a few times (happily, since the bottom is just sand/mud, there is little chance of damage).