1. The Ocean as an Acoustic Medium.- 2. Ray Theory of the Sound Field in the Ocean.- 3. Reflection of Sound from the Surface and Bottom of the Ocean. Plane Waves.- 4. Reflection of Sound from the Surface and Bottom of the Ocean. Point Source.- 5. Propagation of Sound in Shallow Water.- 6. Underwater Sound Channel.- 7. Range-Dependent Waveguide.- 8. Antiwaveguide Sound Propagation.- 9. Scattering of Sound at Rough Surfaces.- 10. Sound Propagation in the Random Ocean.- 11. Scattering and Absorption of Sound by Gas Bubbles in Water.- References.