Details from the depths

After returning from a photo shooting session yesterday, I found that I had a sequence of a few shots in the middle that were drastically underexposed, though those before and after were fine. I believe that I inadvertently pressed the AE-Lock button for a few seconds, holding the exposure that would have been appropriate for reflected sun on a patch of water. The results manifested with auto-ISO sensitivity at the camera's minimum ISO setting of 100, while surrounding frames auto-set to ISO 400 or 500 along with a similar shutter speed and aperture. In any case, it's hard to identify the birds in this image as Black Scoters because, well, almost everything is black. 

Was there much data collected within the darkness, though? I opened the image in RawTherapee and applied 3 stops of exposure compensation, yielding the following:

 

Quite a bit more to see there. I'm impressed. There's some noise to be seen, and I certainly wouldn't make a intentional practice of underexposing by 3 stops, but it's nice to see that it's still possible to extract a decent image.