Dive computer (depth, time, NDL)

A dive computer is a digital device that monitors your dive profile. It calculates how much nitrogen enters your body while you are underwater. You wear it on your wrist like a watch. Most models show your current depth in meters and your remaining No Decompression Limit (NDL). I once saw a diver in Koh Tao ignore his NDL because he felt fine. This was a mistake since the computer tracks nitrogen buildup that you cannot feel. Always check your air pressure alongside your NDL readings during every dive. Use a reliable brand like Shearwater or Suunto for better accuracy. A broken device is dangerous because it provides zero data when you need it most.