Fluorescence - Glow in the dark:

Fluorescence means in simple terms under certain circumstances, the "glow" of normally not really luminous materials. That this is in simplified form, to the conversion of radiation from an invisible to our eyes wavelength (eg UV light) in a visible wavelength (color).

My underwater fluorescence photos: Fluorescence gallery

Download for more information about fluorescence: Interview with Georg Nies (german)

Download a comparison of 3 different fluorescence filters: Fluorescence filter comparison