10 tips for selecting underwater dive lights for cave diving

10 tips for selecting underwater dive lights for cave diving


Cave diving is an extreme sport involving exploration of water filled caves. This is done for pleasure, exploration, scientific research and search and recovery. Cave diving uses scuba equipment in specialised configurations. Compared to other sports, there are relatively few practitioners of cave diving, due to the specialised equipment and the skill sets required. Diving lights are essential for cave diving and selecting the right ones for the job is critical. In this blog we will discuss ten tips to select underwater lights for cave diving.

1.    Canister vs flashlight

Canister lights have battery packs with a separate head. This allows for easy maneuverability of the light head while keeping the large battery pack secured out of the way. These lights are best for primary lights.


Handheld flashlights are usually limited by size. They typically do not burn as bright as their canister counterparts due to the size limitations of the batteries. They are also a lot more affordable and compact. This makes it easy to travel with. They are mainly used as backup lights in penetration diving.

2.    Length of canister light cord

Size matters. Measure the distance from your right hip to your left hand when slightly extended in front of you to get an idea of how long the cord should be. This is the traditional configuration for cave diving. If the cord is too short it will hinder your dive.

3.    Depth rating

Make sure the lights you dive with are rated for depth you dive at. For example, a light rated for 100ft should not be carried out to deeper waters, it can develop stress fractures and malfunction. Do not use a “waterproof” flashlight for your diving, after a certain depth as pressure builds up, the lights can simply malfunction leaving you in the dark. 

4.    Beam width

Traditionally lights with a narrow beam are used for cave diving. This allows for the light to be focused into a bright beam. A bright beam of light is also excellent for signaling during a cave dive as light signals are used rather than hand signals for communication.


A lot of primary lights can be focused by moving the bulb closer or further from the front lens. The downside of this configuration is that it is a moving part that can malfunction during a dive. Lights with a constant beam angle of around 10 degrees make good primary lights.

5.    Brightness

In cave diving, a bright light provides good visibility and spatial awareness. There are some situations where brighter is not always better:
  • Debris and silt can cause distracting reflections from a bright light.
  • Bright lights can blind your dive buddy when accidentally flashing it in his eyes.
  • A very bright light will use more battery power resulting in a shorter burn time.

Some of the newer LED lights have different brightness settings allowing you to adjust for these situations on the fly.

6.    Weight and buoyancy

When selecting a light, it is important to find a light that has neutral or slightly negative buoyancy. Older canister lights had square batteries in round canisters. These lights had lots of air trapped in the canister that gave it positive buoyancy. This is not the case with the newer lights.

7.    Light bulb selection

It is better to use led underwater  lights (Light Emitting Diode); it is by far the most popular technology in the market now. Although, there are ‘halogen’ and ‘High Intensity Discharge’ (HID) lights available, LED stand out to be the best. The LEDs contain tiny chips and are extremely rugged. They are bright, reliable and energy efficient.


HID bulbs are notoriously expensive and can blow easily when bumped or switched off and on. They are also prone to malfunction when a bad connection cycles them on and off.

8.    Switch position and type

Having a waterproof switch is essential for dive lights. Water entering the light leads to corrosion and malfunction. Two types of switches are popular in modern dive lights:
  • Rotary switches
  • Magnetic switches

The rotary switches use o-rings to keep the water out and are popular in smaller lights like backup lights. They can fail to provide a good watertight seal if the o-rings are not well maintained.


The magnetic switches are completely watertight and do not require much maintenance.


The location of the switch can also make a big difference in convenience and usability of canister lights. Switches located on the light head of a canister light are easily accessible and it means that the canister can be mounted out of reach of the diver. Switches on the canister are also common but that limits the mounting possibilities of the canister to somewhere within reach, traditionally the right hip.

9.    Selection of Batteries

When making the choice between rechargeable and disposable batteries, it is good to keep the following in mind: Always use new, high quality, non-rechargeable batteries for backup lights. It is usually a good idea to have rechargeable dive light batteries in your primary light.

10. Maintenance

Always follow the manufacturer’s instructions for maintaining the light. As all the lights are water-tight, maintaining them is simple. Give them a fresh water rinse, dry and store them carefully. Many of the models contain O-rings, which need to be dried and lubricated after each use. Be careful with the disassembly not to damage or lose the o-ring and use approved substances (silicone lubricant) for lubricating the O-rings.


By following these guidelines you should be able to make an informed decision for selecting a good light for you cave and wreck diving adventures.


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