The existence of a wide bed of the crinoid Leptometra celtica (M’Andrew and Barrett 1857), at approximately 500 m depth, off the Portuguese south coast is inferred from remotely operated vehicle (ROV) transects carried out as part of a research project (IMPACT) aimed at evaluating the impact of bottom trawling on the burrowing crustacean Norway lobster (Nephrops norvegicus) fishing grounds. The crinoid bed is located in an enclave of gravelly sand surrounded by muddy sediments, the latter constituting the typical habitat of Norway lobster. An overall description of the geological and oceanographic features off the Portuguese southern coast is presented, highlighting the complexity of factors influencing the research zone. A delimitation of the crinoid bed and a comparison of taxa richness for the epibenthic megafauna of the adjacent towed zone are carried out. This finding highlights the urgent need for a comprehensive mapping programme to allow for the identification and preservation of sensitive habitats within the scope of the European Union Habitats and Marine Strategy Framework Directives.