Traveling to Iquitos, Peru
Really, there are only two ways to travel to Iquitos, Peru. The fastest being by plane, the other by boat. All flights into Iquitos have their origin from Lima. The greedy special interest airport gods of Lima and Cuzco would prefer you do not go to Iquitos, they have little to no investment here. So untill that changes, your flight will be coming from Lima, Peru with possible stop over in mountain jungle cities such as Tarapoto or Pucallpa.
The other lengthy but super interesting way to get here is by boat leaving from Pucallpa or Yurimaguas (upstream from Iquitos) Pucallpa is the Ucayali River and Yurimaguas is the MaraƱon River. There are speed boats that can make the trip shorter but the slow boats are fun if you have the time to enjoy all the scenery. Rent a cabin to keep your belongings safe!
The other Option By boat is to come in from Leticia, Colombia or Tabatinga Brazil on the Main Amazon River. There are speedboats that make the trip in 8-10 hours or once again the slow river taxis that will take several days to reach the destination.
High water is better for travelling by slow boat