Forgive an all-digital guy this intrusion. I like you guys, I really do!
There's been some discussion about how film renders water a particularly pleasing blue. A came across this while researching an unrelated issue. Look at figure 3.3 here: http://www.cg.tuwien.ac.at/research/theses...vic/node23.html
Basically, film has different response curves for red, green, and blue resulting potentially in blue shifts at the bright end of the exposure range. This certainly doesn't explain everything but it could perhaps contribute to the phenomenon. Perhaps certain films have a pronounced response iregularity that contributes to their especially good performance underwater.
