Bad news for marine mammals...
The Navy is allowed to use mid-frequency active sonar (whatever that is...) and a sensor that uses small explosives.

http://www.defenselink.mil/Releases/Release.aspx?ReleaseID=10427

active sonar is when they broadcast to get returns off of objects ('pinging') as opposed to simply listening (passive)...

i cant speak with any knowledge on the frequencies used...

From the Naval website... http://www.whalesandsonar.navy.mil/stranding_events.htm

"The Navy and NOAA Fisheries learned from the Bahamas stranding that certain marine mammals, particularly beaked whales, may be sensitive to mid-frequency sonar."

Well, it isn't as bad as the broad band sonar that the other navy's use. I don't think the Russians, etc,care too much about the whale population.

The Soviet Navy also had a habit of disposing of problematic reactors from nuclear submarines by tossing them overboard in deep water, I believe. Around when the Berlin Wall came down, the LA Times also had a very astonishing map of the USSR showing all of the peace-time uses of nuclear weapons. For things like blowing toxic gas out of mines, or detonating a bunch in a line to dig a canal. As much as we may be annoyed at the US Navy, the fact that we allow dissenters to the point where they feel obligated to put up that page at least shows that they don't think they can apply the "we'll do whatever we want and we don't care what anyone thinks" justification with complete impunity...

I'm sure the testing of these (http://en.wikipedia.org/wiki/Nuclear_Depth_Bomb) was, er, considerably worse for marine life than any sort of sonar.