Although it has been recognized recently that deep-sea areas might be characterised by benthic “hot-spots”, research on trenches has so far recognized the oligotrophy of these environments both in terms of available food sources and density of benthic organisms. In September 1997, an international expedition promoted by the Istituto di Scienze Ambientali Marine of the University of Genova, involving European and Chilean institutions and with the cooperation of the Servicio Hydrográfico y Oceanográfico de la Armada de Chile, was carried out on board the vessel Vidal Gormaz to study the benthic ecology of the Atacama Trench, which, due to the extremely high productivity of the area, could present special characteristics.