Taken with a Nikon D90, 1100mm f10 lens, 1/4000s exposure @ISO100. Electronically stopped down by 5 stops. No filters used. Minimal image processing.
The final seconds before Sunset saw several vivid green scintillations until this photo was taken half a second before the Sun finally disappeared below the sea horizon.
This followed a mirage effect known as the Omega Sun which reflected on the sea and looked like the captial Greek letter.