In order to better understand the cause of low acoustic reflectivity of the Florida manatee (Trichechusmanatuslatirostris), a series of measurements were taken from a stranded animal post‐mortem. The samples came from an adult male that was struck and killed by a boat in April 2004. These measurements were used to calculate the speed of sound, density and attenuation within each sample. To achieve a good statistical representation, many subsamples (connective tissue, blubber and muscle) were extracted from ventral, dorsal and lateral samples collected from approximately the midpoint of the body (at the umbilicus). Results for the connective tissue samples indicate an average sound speed, density and attenuation of 1725 m/s, 1089 kg/m3 and 5.21 dB/mm, respectively. These results establish a reflection coefficient of 0.12, or, in other words, only 12% of the incident acoustic wave is reflected in the water–skin interface.