Figure 1.

Tripterygion delaisi displaying its conspicuous red iris fluorescence at 30 m depth. Picture taken with Nikon D4, LEE 287 Double C. T. Orange filter, and manual white balance, without postprocessing (Nico K. Michiels). Note that LEE 287 is not a long‐pass filter (as is, e.g., LEE 105 Orange or LEE 106 Primary Red). It is used to correct a bluish cold‐white scene to a warmer spectrum in photography (C. T. = “Correct to Tungsten”). Combined with Manual White Balance, this results in pictures that show colors at depth, including fluorescence, as perceived by a human diver