This script acts as a red fitler on diving photos.
To launch it, goto the menu /Script-Fu/Enhance/Diving red filter
Basically, create a new layer containing the corrected picture
You can adjust the red level (sometimes, green might works better !)
and set if the white balance has to be performed...
(Copyright: Thomas Amory - right: before/Left: after)
(Copyright: Thomas Amory - right: after/Left: before)