Tabatinga is a city in the north-western part of the state of Amazonas in Brazil. It forms a contiguous settlement with the Colombian town of Leticia. Santa Rosa on the nearby island in the river is in Peru.
Movement between all three countries' border towns is unrestricted; but of course, make sure you're stamped into the correct country if leaving the border area. Try to minimize the amount of times you go through immigration: i.e. if entering the region from one country and leaving from another, just get one exit and one entry stamp - even if you visit all three towns in this area. Anything more seems to annoy the immigration officers.
The Brazilian immigration office is located some way down Tabatinga's main avenue, Avenida da Amizade.
The Colombian immigration office is at the airport, so if you're flying in and moving on to a different country you may as well get an exit stamp when you land. Don't wait several days between getting your exit stamp and the next entry stamp; however leaving it one day doesn't cause any problems.
The Peruvian immigration office in Santa Rosa is fairly central and easy to find, just ask someone.
Update August 2019: It is no longer necessary to travel across the river to Santa Rosa to get your Peruvian stamp. Joint Colombian and Peruvian immigration is located on a pontoon boat permanently moored in the river, and connected to the center of the main dock in downtown Leticia. For all journeys between Peru and Colombia, this is the only spot you will visit for all immigration procedures. If you are arriving by boat, walk over to the pontoon to get your Peru exit stamp and Colombian entry stamp. If you are departing Colombia for Peru, go to the pontoon before you board the boat. Both countries work in the same office, side by side.
If coming from Manaus, it is quite simple to catch the boat to Tabatinga. There are two options, the fast boat and the slow boat. For the fast boat, go to the 'Terminal Ajato' at the wharf in Manaus and book directly with them. You can find this by going to the market near the wharf, then walk east until the road curves around. The booking office is on a modern floating pontoon. There will be hawkers outside, but just go on the pontoon and book direct with the Terminal Ajato office there. Make sure to bring your passport. For information on departure times you can view their website . The cost of the fast boat is 680 reals. The journey takes about 36 hours and includes food. From Tabatinga it is a short taxi ride to Leticia. For the slow boat it is 380 reais and it will take 6 days to go.
All three currencies are generally freely traded in the town, though Peruvian Soles may not be willingly received. Changing money is not difficult though.
"Fazendinha", where there´s good pizza!
"Tres Fronteiras" restaurant has a beautiful garden and a romantic atmosphere. They specialize in BBQ and Peruvian food and are known as the best restaurant in Tabatinga.
"Vinicius" bar, on the main street.