First, you will need to go to the Settings > DCC and choose from Blue or Green DCC (depending on which water you will dive in)
You can toggle DCC on/off by pulling the activation switch three times while in power- or video-mode.
The rule is that DCC should be used whenever there is enough natural/ambient light.
White Balance (WB) should be used in low light conditions (e.g. greater depths, cave diving or night diving).
Make sure to never use DCC with external lights, as it will discolor the footage.
For more information on Depth Color Correction, read our DCC guide here.