This paper has two main objectives: (i) to discuss essential concepts of the ecological approach to composition, proposing the term eco-composition as a common reference for theoretical perspectives and compositional techniques; and (ii) to present the multimedia piece Vivir sin después, realised within the context of the Paititi Project. Following the Introduction, the paper is divided into two main sections. In section 2 we discuss issues raised by the application of the ecological approach to composition. Regarding the data-gathering procedures, eco-composition provides two effective methods: re-enaction and anchoring. Organisation of sonic materials is done through accumulation of heterarchical layers, giving rise to emergent musical phenomena. Section 3 dwells on the compositional strategies applied in the multimedia installation Vivir sin después. We describe the process of re-enacting the first Spanish trip through the Amazon River Basin, carried out by Francisco de Orellana and fifty-nine Spaniards in 1541. Then we address technical aspects of the piece, such as the application of multiple views of single entities, the development of non-hierarchical forms and the manipulation of sonic fields.