Ayahuasca, or spirit vine, is the key ingredient in a plant mixture that shamans of the Amazon have used as a psychotropic healing method for centuries. At the ayahuasca ceremony, shamans lead small groups in consuming the hallucinogenic drink and then act as guides as each person enters their own highly personal, unpredictable journey through the mind. The drink is used to cure almost every complaint, from physical to mental.

One crucial tool shamans use during the ceremony are icaros. These melodies, which come to the guides during visions, are eerily beautiful and thought to be the purest essence of surrounding plants and animals. Shamans highly prize icaros, as each wordless song is another piece of knowledge about the infinite mysteries of the rainforest.

Now Soundwalk Collective’s Stephan Crasneanscki has attempted to film the unfilmable: the trip through the subconscious that begins with the ayahuasca ceremony.

PLANET spoke with the French filmmaker about journeying up the river.