An environment measurement system according to the present invention is provided with a first unit comprising: a transmitter which is located undersea and transmits an acoustic wave in a designated direction a plurality of times; a first receiver which is located undersea and receives an acoustic wave reflected by a reflecting body at the sea surface or the seabed; a transmission direction setting unit which designates, to the transmitter, transmission directions specified in advance by a user, so as to cause the transmitter to transmit acoustic waves in the directions; a first necessary time measurement unit which, for each of the transmission directions, measures from the transmission and reception times of an acoustic wave a time necessary for the acoustic wave to return, as a necessary time, and outputs an average of the measured necessary time as an average necessary time for each of the transmission directions; a layer setting unit which partitions between the sea surface and the seabed into layers each
