[mpyne]

Salinity, temperature and pressure aren't normally large factors for cetaceans, no.

If you're referring to active sonar, that's an issue for anything with ears under the water. But animals themselves also can make loud noises (e.g. the sperm whale can reach 230+ dB), as can surface ships with their own active sonar kits.

[euroderf]

AIUI the problem has been the USN making absolutely huge noises and the relevance being that the noises carry very long distances, affecting wide areas of habitat.