Yasuni National Park (Parque Nacional Yasuní) is an Ecuadorian national park near the Peruvian border.
Coca and Nuevo Rocafuerte are on the Ecuadorian side of the border. There is a daily speedboat service between the two (US$15, 10-11 hr). Ecuadorian immigration is located in Nuevo Rocafuerte. Pantoja is the first village on the Peruvian side, and here you need to get your entry/exit stamp. Santa Clotilde is the biggest town between Mazán and Coca. Sometimes slow boats from Mazán terminate here, and there is also a scheduled speedboat service (S/100, 8 hr). Mazán is the strategically located across a narrow strip of land at a huge bend between the Amazon and Napo rivers. It is a short boat ride from Iquitos (S/7-15, 40 min-2½ hr).
Tours to Parque Nacional Yasuni can be arranged from Coca or Nuevo Rocafuerte (about US$60-90 per person per day if arranged in Nuevo Rocafuerte, which is the most economic option).
All in all, there are 4 guides in Nuevo Rocafuerte. One of them is Louis Ramos who offers also multi-day tours with camping by Laguna Jatuncocha or in other bespoke locations of the park - these are all locations at very pristine primary rainforest, the nature here is very wild and untouched. Usually during the tours it is possible to see monkeys, parrots, caimans, dolphins, many species of birds, giant trees, different types of beetles and insects, beautiful butterflies, piranhas and other species of wildlife. The tours also include explanations of different types of plants as traditional medicine. Louis is happy to accommodate any suggestions and requests for the tour, he has also led expeditions to see anacondas and black panthers. It is possible to contact Louis through his sons Raul: +593968095176 or Louis: +593989941195 (both have whatsapp).
Take a boat up or downstream, relax and take in the scenery.
There is no ATM between Coca and Iquitos, so bring enough cash. Changing money at either of the border towns, however, will see you receive an extremely bad rate.
You will likely eat a lot of rice-based meals while on the Napo River.
The locals make a liquor from fermented sugar cane and honey, sometimes mixed with milk. Try at your own risk.
A mosquito net is a good idea if you plan on sleeping in a hammock and repellent is a must.
There is no 3G signal on the Peruvian side north of Mazán. There is municipal internet access in Santa Clotilde. There are medical clinics in the bigger villages.
Iquitos and Coca are the main jumping off points.