The Nikon 200mm F/4 Micro is an old design lens, no stabilisers, no focus drive motors. So it is quite slow and will get blurry if you are not super steady – I would definitely suggest this lens only to those who are looking for a new challenge underwater or if you’re shooting extremely shy animals. It’s also quite heavy, but feels solidly built with nice balance when used above water. There are many reviews on the lens around the internet – if you’re also into dragonflies and other skittish insects this lens will already be on your radar.
These days it is pretty hard to choose from all the diopters available – you probably have at least one old school one in your kit bag. The Inon UCL 165 and 330 were the first mass produced diopters specifically for underwater use, before those we had to use slide on single element diopters (woodys diopter), or put a higher quality dual element diopter directly on your lens before you got in the water (Nikon 6T).