Observe and capture the brilliant fluorescent glow emitted by coral, jellyfish, and other sea life with this Ikelite Dichroic Excitation Filter for their DS161, DS160, and DS125 underwater strobes. For best results, combine this with an optional yellow barrier filter for your camera housing's lens port and another for your dive mask. The Dichroic Excitation Filter allows you to use your existing strobe setup to bring out fluorescence, the radiant phenomenon produced by select organisms as a result of exposure to a particular wavelength of light.
Fluorescence is mostly visible in greens, blues, and reds. Shining your filtered light source on sea life and photographing the resulting glow is best done at night or at depths great enough to block out sunlight. It may be possible to do it in more shallow water during the day by underexposing ambient light and further experimenting with your setup.