We find getting a shore excursion off ship and if 4 of you a taxi is very good, they will give you a price and show you a map of where they will take you and make shure you take USA $ and small notes
I went to Manaus in 2006 on a P & O ship Artemis. This was a 38 night cruise from Southampton and back. We loved the cruise but not the ship and glad to see the ship leave the group.