52 ENVIRONMENT | MT 5211 natural environment | BT1 sea-bed | BT2 marine environment | BT3 aquatic environment | BT4 physical environment | RT maritime area [1231]
52 ENVIRONNEMENT | MT 5211 milieu naturel | BT1 fond marin | BT2 milieu marin | BT3 milieu aquatique | BT4 environnement physique | RT espace maritime [1231]