What is the primary challenge when transmitting sound through seawater?

The primary challenge when transmitting sound through seawater arises from varying temperature and pressure. Sound propagation in water is significantly influenced by these factors, as they can alter the speed of sound. In the ocean, temperature and pressure vary with depth and geographical location, leading to conditions such as thermoclines and pycnoclines, which can create refraction and scattering of sound waves. This variability complicates the transmission of acoustic signals because it can cause them to bend, change intensity, or even be absorbed, affecting the clarity and accuracy of underwater communication and sensing.

Other factors like salinity, water clarity, and marine life do play roles in sound transmission, but their impacts are generally less pronounced compared to the effects of temperature and pressure, which have direct and significant implications on sound speed and wave behavior underwater.