When combined with a wet macro lens (diopter), super macro photography is within reach. The tiniest details of the smallest subjects can be captured with this set up (once you get a little practice in of course). With the RX100 VI we recommend using the Bluewater +7 if you are just getting the hang of macro and super macro photography. The Nauticam Compact Macro Converters (CMC-1 & CMC-2) are top of the line wet lenses with amazing lens sharpness but have a lot of magnification and can be a little more difficult to use.
The GH5s is popular for underwater video because the camera is at a great price point, the body is relatively small, there is a multitude of micro-four thirds lenses available for any lens requirements, the video bitrate is quite high, and camera supports many video features that other micro-four thirds cameras do not support. It crushes all other micro-four thirds cameras at high ISOs with respect to noise.
Before you start digging into the reviews, a few notes on choosing a cam that's right for you. You'll definitely want to consider frame rate, expressed as frames per second (fps). Some action cameras offer up to 240fps recording, while others only go to 30fps. For standard playback, 30fps is perfectly fine. It's when you want to slow footage down in editing to create dramatic scenes that frame rate matters. Footage captured at 240fps can be slowed down and played back smoothly at one-quarter speed. You may also want to go for a cinematic look, in which case you'll want one that has a 24fps capture option, the same speed used by most Hollywood productions.