Bioluminescence off South Africa

Whilst steaming at approximately 12 knots in the area between the Alphard Banks and Cape Agulhas, and 25 miles offshore, my ship transited a large area of bioluminescence. Conditions at the time were: wind Easterly force 6, swell South Westerly at 4.0 metres, sky completely overcast. The whole surface of the sea as far as the eye could see was covered in a faint glow. The ship's wake was like a solid bar of light stretching to the horizon astern. The bow wave was very bright, and every breaking wave crest could be very distinctly seen as a bright source of light.