5. Use Macro mode
If you’re trying to get close up shots of your subjects, you could benefit from the macro setting of your camera to give you the most accurate and timely focus. The Macro setting automatically prepares your lens to focus within a smaller range, so it will prevent it from hunting to find a focal point.
A word of warning, you will run into problems if you suddenly change course and shoot something further away, so know the limitations of your macro mode and be prepared to turn it off if necessary!
6. Familiarise yourself with your camera above water
As when you shoot above water, in darker conditions, it can be tricky to identify settings or buttons on your camera. For this reason you should identify and master the key settings when you are on land, so that you can recall them with greater ease if necessary later on.
Your main camera settings should be locked in before you dive in, so that you won't be forced to change anything too much when it is already difficult to do so.