Less than a mile west of the town of Puerto Iguazu, there is an impressive sight where the Iguazú River meets with the Paraná River. This creates a “T” intersection with three land masses. In this case, the three land masses are portions of 3 different countries.
In Spanish, “frontera” means border, so here the 3 borders are Argentina, Brazil and Paraguay. Each country has installed a marker with the colors of their flag: blue and white for Argentina; red, white and blue for Paraguay; green and yellow for Brazil. Therefore, from this spot, tres fronteras, you can view all three markers (Brazil’s marker is a little hard to pick out since the color blends in with the trees).
Argentina’s marker
Parana River-Paraguay on the other side
Walkway along Iguazu River
Brazil’s marker-above and to the right of center
Paraguay’s marker
Second Act 
Been there, done that, on a river boat for about 6 hours on a Sunday, before the terrorist took over that portion of Paraquay. Very interesting part of the world.
Pingback: Look Back: Iguazú Falls | Second Act