Why dive at night
A reef changes completely after dark. Many daytime fish shelter in the coral to rest, and some parrotfish wrap themselves in a mucus cocoon. Animals that hide by day come out to feed: octopus, lobsters, crabs, shrimp, eels and many kinds of shellfish. Coral polyps extend to feed. In some places the water glows with bioluminescence when you move your hand.
Your light also restores the full color of everything it touches. By day, water has filtered out most of the red, as explained in light and color underwater; by torchlight, reds and oranges show as they really are.
Gear
- A primary light bright enough to see clearly and signal.
- A backup light in case the main one fails.
- A marker light on your tank or snorkel, such as a small strobe or glow stick, so your buddy and group can find you.
- A whistle and a surface light for the boat at the end of the dive.
- The same gear you know. Night isn't the time to try new equipment.
Charge or replace batteries before the dive and check every light at the surface.
Signals at night
Normal hand signals still work if you shine your light on your own hand so your buddy can see it. Never shine a light into another diver's eyes. Lights themselves are used to signal:
- OK: move your light in a slow circle.
- Attention or problem: sweep the light quickly from side to side.
- Look here: hold the beam steady on what you want to show.
Planning the dive
- Choose a site you've already dived in daylight, with an easy entry and exit.
- Plan a shallower, simpler profile than you would by day.
- Agree buddy positions, signals and what to do if you lose each other: cover your light, look for your buddy's glow, then ascend if you can't find them.
- Enter at dusk if you can, so your eyes adjust as the light fades.
- Have a light on the boat or shore to navigate back to.
Being kind to marine life
Bright lights can stress or blind animals. Avoid holding a beam on one fish for a long time, and don't chase animals into the open, where predators may catch them. Good neutral buoyancy matters even more at night, when it's harder to judge your distance from the reef.
Training
Many agencies include a night dive in the advanced open water course and offer a night diving specialty. A first night dive with a guide or instructor is the best way to start.
Frequently asked questions
Is night diving dangerous?
Not when planned well. The main challenges are navigation and staying with your buddy. Choose a familiar site and dive with a guide the first time.
What do you see on a night dive?
Octopus, lobsters, crabs, shrimp, eels, sleeping fish and feeding coral polyps, and sometimes bioluminescent plankton.
What does circling your light mean?
It's the "OK" signal at night. A fast side-to-side sweep means "attention" or "problem".