Using the Navy's underwater submarine listening system, Christopher Clark has been able to track deep water whales, like the blue whale and fin whale, throughout the ocean basins.

These animals use sound to communicate over very long distances; for example, a whale singing off the Grand Banks of Canada can be detected in Puerto Rico! But as the number and noise of commercial ships has increased, it is likely to interfere with the whale's ability to hear one another. What the long term effect of this will be on the whales is largely unknown.