[Cussy]

Tazzie,
Unless I know 100% what is going to be there, I don't have "a" shot. There are a range of shots maybe, but not a single thing. This way I wont be disappointed.

Saying that though there were one or two dives at St Abbs recently where I had an idea. On one I wanted some really good close-up and abstracts of Plumose anemones. I nailed that one as there were plenty around. I also did a dive looking for subjects to back light. While I had ideas I didn't exactly know what to expect, so this was more of an idea than a true vision.

I recently did a dive at Stoney where I had an image in mind. I wanted to mess around with long exposures, so I added a tripod. I didn't achieve what I wanted (a really good natural light shot of the Stanegarth), but I learned enough in that dive that I'm confident I can nail it next time.

So I'd say it's far easier to get what you visualise if it's static (like Plumose or wrecks), but when it comes to fish or anything that moves you rely quite a lot on luck, so this is when you need an idea of "if I see a crab I'll try X", "if I see a fish I'll do Y", "if the vis is so shocking I'll do self-portraits" etc

I'm only just getting into the realm of coming up with ideas and following them through. I find this approach can be disappointing though.
Rob