We had a sailing boat when I was young and ran on a cay only one time in all the years we were out sailing. I' ll never forget it because we could not get of ot without help from a couple in another sailing boat. I found it on Google maps. You can see the the cay in the white square kiind of drawing I made. It's from Luleå archipelago in north of Sweden. The cay and the island is called Dödmansgrundet (Dead man cay) for some reason.??.