Samples of water from the site where the body was found or where the immersion probably occurred are collected in clean containers and isolated from extraneous detritus by overnight sedimentation. The gross volume is carefully decanted, the remainder is centrifuged, and the deposit is examined under dark-field microscopy to determine if diatoms are present. For taxonomic purposes, the desired end product for scanning electron microscopy is a dried sample without artifacts. Diatoms possess a solid exoskeleton, do not require fixation, and are sufficiently strong to tolerate air drying. The presence of the same species of diatoms in the water sample and in organs other than the lungs is considered indicative of drowning. The scanning electron microscopy method does not alter the morphology of diatoms and allows the study of fresh and sea water species present in the organs of bodies found in the water. The method facilitates the diagnosis of drowning under specific conditions. 26 references and 4 figures (Author abstract modified)