So I called the AA to get travel insurance with them, this is an approximate transcript of the conversation:

Me: Just checking that I'm covered for all my scuba diving, what restrictions do you have?
AA: You can dive up to 30m provided that you are qualified to do so, and you do so with a buddy.
Me: Great, now I noticed something on your website about not being covered for diving with sharks, what does that mean?
AA: We don't insure you for diving with sharks
Me: Does this just mean cage diving, or with great whites or something? I assume if I'm diving on coral reefs and there are some harmless reef sharks around, that I would still be covered.
AA: We don't insure you for diving with sharks
Me: So does that just mean I won't get any payouts if I somehow get bitten by a sleepy harmless reef shark? Or will I not get insured for any of the diving?
AA: We don't insure you for diving with sharks
Me: Erm, ok.

So then I called Campbell Irvine

Me: Just checking you don't have any issues with diving if there are sharks in the water?
CI: We'll insure you providing you aren't cage diving or baiting the sharks.
Me: Yeah, I don't think I will be doing that, thanks.

(Conversations followed on from whether I would be insured for driving a rickshaw across India, and also paragliding. So I think the insurers probably thought I was a little strange)