Hi Luciana,
I will be happy to provide comments and details about our trip, the Saint Paul, the Ariaú and Viverde Services, but we only arrived back in the USA this week and we are still trying to organize our pictures and other details. So I will be able to provide feedback later.
I can tell you without a doubt that our experience was positive in all cases, and one of my friends in Rio is now very interested in making the same trip (I recommended she work with Viverde). One very important detail about the Ariau of great interest to North Americans is that the pH of the waters of the Rio Negro are too low for mosquitoes, which we found to be a very, very positive surprise. I know that many other North Americans would be very relieved to know that fact.
More details to come later this week.
Best regards,
John