I don't know how much time and energy I've spent trying to get a shot of these guys that at least is almost in focus, but it is considerable. In the old days (meaning before November this year) I used a Nikon AW1, which is convenient and waterproof, but has relatively slow autofocus and a tiny little sensor. So I've considered buying a housing for my D500 for a while, thinking that would improve the odds.
In the end I bought a housing for the Z6 since it has a larger sensor and better resolution. The results still don't impress but the image quality is better now.