This work narrates an experience of ethnographic investigation, explaining how and why the investigation  it was approached in an audio-visual way giving step to documentary "Neltume Lake: Kume Mogñen Tain Mapu Mew ". The approached topic is the fight of the Mapuche communities in Neltume Lake, place of the mountain chain of Panguipulli's Commune (the XIVth Region of the Rivers), in opposition to the possible construction of the “Hydroelectric Power Station Neltume”, transforming this audio-visual record in a trip to the deepest of the spirituality and worldview  Mapuche, reflected in the ferreous defense of a territory considered like sacred, and that one sees opposite to the threat that means the possible flood of places that to others of being ancient, are of an incomparable beauty. Here is explained how it came near to the decision (opportunity) to register in an audio-visual way the fieldwork, and that was what contributed this type of record to the resistance of the communities.