Abstract: A system and method of remote sound speed measurement are disclosed. In one embodiment, a system for estimating a sound speed comprises a plurality of transducers configured to i) transmit a first acoustic signal from a first location, ii) transmit a second acoustic signal at a second location, iii) receive a first reflected signal at a third location, and iv) receive a second reflected signal at a fourth location, the reflected signals comprising at least one echo from at least one of the acoustic signals; and a microprocessor configured to i) estimate a travel time based on at least the first or second reflected signals, ii) estimate a travel time difference based on at least the first and second reflected signals, and iii) estimate a sound speed based on at least the estimated travel time and estimated travel time difference.