A study was conducted to analyse the habitat of the Antillean manatee (Trichechus manatus manatus L. 1758) in the Coswine Swamps of northwest French Guiana, South America. Water parameters were similar to those described in other studies: water depth varied from 2.5 m to more than 20 m; water temperature was between 24.5 °C and 30.3 °C and pH varied between 5.5 and 6.9. Salinity was low (0.0‰ to 1.3‰) with 86.9% of all samples taken in fresh water. No submerged aquatic vegetation was found in the study area. A botanical survey along the banks revealed that most plants seem to be potential forage for manatees. Red Mangrove is very abundant throughout the area. It is suggested, therefore, that manatees graze on the bank vegetation, where feeding traces were found, or leave the area to feed. The Coswine Swamps provide a suitable manatee habitat and are able to support a large manatee population. Food supply is sufficient, brackish and fresh water are available, and the site is free from human disturbance. Further studies should be carried out to assess the population size, travel routes and foraging patterns, as well as acquire detailed information about the other manatee habitats in French Guiana.