Increasing interest in the optics of the sea makes it important to be able to measure efficiently the intrinsic optical properties of sea water. In situ measurements are accurate but slow, costly, and difficult in adverse weather conditions. Passive remote sensing techniques measure only one optical parameter whereas two are needed for adequate characterisation of the water. This paper describes a technique for independent measurement of the two basic intrinsic optical properties of sea water: the absorption and scattering coefficients. The technique uses an airborne system that transmits a laser pulse down to the water and records the signal backscattered upwards from particles in the water. Experimental results demonstrating the feasibility of the system are reported. Comparison with in situ measurements confirm the validity of the technique.