Manuel is a Galician writer, poet and journalist. He began his career in some Spanish newspapers like El Ideal Gallego, La Voz de Galicia, El Pais, and was the sub-editor of Diario 16 in Galicia. Rivas has written well known poems, novels, articles and literature essays.

Rivas is considered a revolutionary in contemporary Galician literature. He was a founding member of Greenpeace Spain, and played an important role during the Prestige oil spill near the Galician coast. Some of his work has been adapted to cinema, such as A lingua das bolboretas and El Lapiz del Carpintero.