Inexpensive and reliable LEDs have transformed dive lights in the past ten years. Mark ‘Crowley’ Russell rounds up the best, for everything from an occasional night dive to deep cave penetration Nobody forgets their first night dive. Many divers of a certain age won’t forget their first underwater torch, either. It was big, garishly coloured, had a filament bulb that burned very brightly until just after you jumped, or perhaps went ‘pop’ when you turned it on, out at sea, in the dark, with no spare batteries. Thankfully, time has moved on and today’s dive lights are brighter, smaller and much more reliable than their predecessors. Improvements in battery technology have been dramatic, but the game-changer was the advent of inexpensive, white-coloured LEDs. A diode is an electrical component that allows electricity to flow through it in only one direction, and a ‘Light-Emitting Diode’ – LED – emits light while doing so, through a process known as electroluminescence. The colour of the light emitted can be varied depending on the material used in the LED’s construction. Red LEDs are the easiest to produce and became commonplace in the 1970s in the displays of electronic pocket cal...