I have said this before ....do be careful as a large number of holiday insurance policies do not cover accidents whilst, "rock climbing, "ice skating" and possibly surfing although the latter is open to conjecture. Signing a ship's waver only exacerbates the situation as far as you are concerned. ... Neil.
The rock wall does not actually require any extra insurance, but before you go on it they will make you sign a waver form. They have proper safety equipment and from what I saw the people in charge do actually know what they are talking about. I went on the flowrider and the principle is the same there.
I saw fellow cruisers well over 60 going up the wall and lapping it up !!! Enjoy the experiance I say.