How to take pictures underwater
Unlike video, photos require a fundamental understanding of the relationship between shutter speed, aperture, and iso.
Having full control of those functions will enable you to take more interesting pictures where YOU despite, how your composition looks like.
The Equipment needed for that will include different lenses, ports, and flashlights. Patience is needed, to wait for the right moment and often it takes several shots with different settings to capture the scene or subject desired.