What challenge is often faced during underwater acoustic surveys?

Variability in environmental conditions is a significant challenge faced during underwater acoustic surveys because these conditions can greatly affect the propagation of sound waves in the water. Factors such as temperature, salinity, and pressure can change with depth and location, leading to fluctuations in sound speed and absorption. These variations can complicate the data collection process, making it difficult to obtain consistent and reliable acoustic measurements. Additionally, the presence of currents, marine life, and underwater structures can introduce noise and interference, further complicating the interpretation of the acoustic data. Understanding and compensating for these environmental variabilities is crucial for accurately assessing underwater environments using acoustic methods.