Island/shoreline campground etiquette

I have been looking at places that I would like to visit someday by canoe and have been wondering if there is an accepted etiquette regarding campsites on islands or shorelines that are accessible by boat. For instance if I was canoeing during the day and came to an island that had a campsite on it would it be okay to land on the island for a break, provided I was out of sight of the campsite or at least say 500' away from it? I know that there will likely be a range of views on this question, but I am hoping there is some kind of generally accepted norm. I am a sucker for islands for some reason and always liked to visit them when canoeing by.

Zach