If you haven’t already tried ultraviolet night diving — also called UV night diving — it’s time to add it to your bucket list. Seasoned night divers will be amazed by the way a UV light illuminates the corals and marine life in a new, beautiful way. Many resorts are now offering these fluorescent dives, or ‘fluoro dives,’ and although this is relatively new to recreational divers, scientist have been observing this phenomenon for years. So, what do you need to know to try ultraviolet night diving?
How does it work?
Chemical compounds in the tissue of these animals (mostly corals) react to the UV light. This causes them to fluoresce in bright pinks, purples and greens. When UV diving began a few years ago, a diver would use a blue light and had to wear yellow shades over his or her mask to offset the excess visible blue light. New technology has since made it possible to dive without the yellow filter. Today’s divers use a UV LED, which has a wavelength just outside the spectrum of visible light. This type of light causes the marine-life fluorescence to show, but since it is nearly invisible to the naked eye, divers see only glowing colors.
What equipment should you take on an ultraviolet night dive?
When night diving with a UV LED light, it’s always wise to bring your “normal” night-diving equipment too. This means having a regular dive light and back-up light. It is also important to attach a strobe or marker light to the ascent/descent line location. These dives are best with a UV LED light (as mentioned above). If you do use a blue light, you’ll need yellow filters for your mask.
Staying safe while boat diving with a UV light
Always remember to jump in with your white dive light on so the captain can see you. Make your descent using this light as a guide and attach a strobe or marker to the descent line. If you are new to night diving, use your regular white light for the first half of the dive to get comfortable before switching to your UV light. Once you switch, it will be much darker, so be careful with your navigation and buoyancy.
You can switch back to your white light at any time, and should do so to find your ascent line and exit the water. Always stay close to your buddy, who should follow the same procedures simultaneously. If one of you has your regular torch on nearby, the UV light effect will not work. Conditions should be ideal, with calm waters, good visibility and no current. If possible, dive the site during the day before diving at night.
Enjoy the show
Using a UV light is a great way to experience the underwater world in a completely unique way. Divers can see marine creatures in brilliant, glowing colors, invisible to the naked eye. This effect comes from proteins within many organisms that react to certain wavelengths of light, usually blue, green, orange and red, depending on the protein. Although not all marine organisms exhibit this fluorescence, those that do offer a dramatic visual demonstration. Watch particularly for shrimp, crabs, worms, fish, jellyfish, cephalopods, tunicates, anemones, sponges and corals.
Ultraviolet night diving is particularly enjoyable for children, photographers and those interested in marine biology. Although this fluorescent effect is still not fully understood, you’ll see these creatures in a whole new light after a fluoro dive — even during the day.