The Magdalena Strait is the narrowest part of the river at 2.20 m, after 70 km on the way from the source to the mouth. The slopes consist of more than 70 million years old compacted lava from the volcanoes of "Pelota" and "Purutal". The reddish color of some of the rocks is due to the presence of iron sulphate in the area. In some rocks there are 120 million year old sea shells, so-called ammonites. It is considered a sacred place and most indigenous people built their villages along rivers such as the Magdalena.
Also accessible by horseback riding.