Fluorescent night dives (or “fluo diving” for short) are also known as “fluoro dives” or “glow dives”. It's what happens when night diving with underwater torches that emit fluorescent light. They have grown increasingly popular in recent years because of the widespread appreciation of the nocturnal sea. More and more dive clubs offer fluo diving, and more and more vendors selling torches necessary equipment appear on the market.
A better understanding of the background and basics allows making more of this exhilarating experience. Some people say that fluo diving is like being in the movie “Avatar”.
Here you can experience the amazing Fluo Diving:
Why does this happen
Fluorescence is the physical effect shown by some materials when they absorb high-energy (and therefore short wavelengths) and to re-emit light of lower energy (and therefore longer wavelengths). Check out the schematic picture.
Other sources of energy may also cause the same effect, such as for example high-speed electrons in cathode ray tubes.
This phenomenon not only occurs in living organisms but also in minerals. “Fluorite” or “fluorspar” is the crystalized rock form of calcium fluoride and is also the mineral that gave this effect its name. When heated this material generates thermoluminescence, thus creating the "fluorite phosphorescent effect" we recognize as glow-in-the-dark.
Learn more about fluorescence
Fluorescence should not be confused with phosphorescence that you know from your dive tech or glow-in-the-dark toys. Phosphorescence has the capability to store light, and re-emit it over a longer period of time, which is therefore not the same.
The phosphor coating on the inside of cathode ray tubes and fluorescent tubes (neon lamps) provides both fluorescence as well as phosphorescence (the familiar afterglow).
This is also why you will find an option “fluorescent light” under the white balance menu in your digital camera. This is not the correct setting for underwater fluorescence photography and filming, though! More on that in a later article on Fluorescence Night Diving!
Have you ever experienced Fluorescence Night Diving? What do you think about it? Leave a comment below!