What is the most significant factor that affects the speed of sound waves in water?

The speed of sound waves in water is primarily influenced by temperature due to the relationship between temperature and the energy of the water molecules. As temperature increases, the energy of the molecules increases, allowing them to transmit sound waves more quickly. This is because sound travels through the vibrations of molecules; when the molecules are more energized and moving faster, they can transfer sound waves more efficiently.

While salinity and pressure do affect sound speed in water, their impact is generally less significant compared to temperature. Salinity can change the density of the water, and pressure can influence it as well, especially at greater depths, but these effects tend to be more subtle. Frequency does not directly affect the speed of sound in water; rather, it influences the wavelength and perceived pitch of the sound. Therefore, temperature stands out as the most significant factor influencing the speed of sound in water.