Why don't they hold the G8 summits on islands?

I was following the G8 summit and the protests against it over the last days and I have to say that it really made me shiver to when these idiots went on their violent rampage. There are a thousand good reasons to protest against the summit, there are also hunderets of good reasons to hold such a summit, but no matter how badly you want things to change with violence - especially against cops who are only executing their duty - you are in fact the most counter-productive force possible.

[side note: there is actually speculation whether the rioters in Genua were masked provocateurs with the mission to discredit the globalisation critiques]

There is one aspect of the G8 that i do not understand: Why are the summits on such accessible locations? Wouldn't it be much cheaper, less prone to recieve bad media coverage and above all more secure to have these summits on a small island, like Helgoland, or aboard a ship, like the Roosevelt and Churchill at their famous secret WWII Atlantic Charter negotiations?