From "Warning Order" by Jamie Fredric

A British bomber has crashed into the Mediterranean and Lt. Grant Stevens is the officer in charge of the dive team:

As the rubber boat skimmed over the two foot swells, Grant knelt down in the center, steadying himself as he worked quickly to put on his scuba tank, fins and mask.  The coxswain pulled back on the throttle.  The boat was still fifty feet from the chopper when Grant hit the water.

By now, the helo was almost totally underwater, only the tip of a red star on its remaining twin tail fin was visible.  One rotor blade poked up through the water's surface.  Grant stroked like hell, finally coming close to the front starboard side of the chopper.  Sunlight filtered through the blue-green sea water, making visibility crystal-clear.  He immediately spotted someone in the cockpit.  Recognizing the chopper as a KA-25, he knew it would be fruitless to try and open the pilot-side door.  He swam directly for the open cargo bay, propelling himself to the forward section, pulling his knife from his thigh strap.  The chopper was beginning to sink faster, as if being drawn downward by a powerful magnet.