Divers prepare to descend after entering the water from KoroSun Divers’ boat Bligh Explorer at Turtle Alley off Vanua Levu, Fiji. This was shot with a GoPro Hero 4 mounted in a 6 inch dome port which allows for images which are partly underwater and partly above the surface. In choppy conditions, it’s tricky to time things such that the waterline falls in the right part of the image but, as with many action scenarios, take enough exposures and you’ll almost-definitely find at least one good one in the mix.
For the technically inclined...