This is a 5 minute (300 second) exposure of the Hauraki Gulf. The sun had already set so light conditions were already dim. I dragged the exposure out to 5 minutes by using a 6-stop ND filter. The only light hue left was this blue shade.
A light vignette has also been employed in the final edit to accentuate the central, lighter zone. You can see Rangitoto Island right on the horizon. I'm perched on the rocks, just above the surging waves.