We went on the "Meeting of the Waters" tour on our way to the Amazon EcoPark Lodge which made it a long and slow boat ride, but well worth it.
Although it rained a couple of times (and they pulled down the tarps on each side of the boat to stop us from getting soaked), we still got to see a lot of the activity and scenery along the large wide river.
It was interesting to see the 2 rivers up close and how they never mix (due to the differing Ph acidity levels, different speed of the rivers, water densities, pollution [one by leaves from the rainforest and the other being silt from the mountains] and different temperatures).
We stopped for lunch at a "floating restaurant" which had a surprisingly nice buffet.
Well worth visiting this amazing aspect of nature