Hidden treasure - Help :( (Spoilers)

[Lord Commander Dante]

OMG!
I'm going out of my wits!
I can't seem to find a way on how to open this chest. Im going to attach a screenshop, please help me out!
P.s - Screenshot is in Witcher's Sense mode, chest doesnt even glow in yellow!

http://i.imgur.com/xnNZ3oB.jpg

***Spoiler***
The location is near Birna's dead body, which is chained to a big rock. North of Sund.

[sirBlue]

If you can not interact with it then it is also not very likely you will ever open it. Devs probably left a broken chest in the game (it happens sometimes). It would not surprise me if there are more chests like this one to be found on the map.

[Caelum_Errare]

Dont listen to that guy, there is a body on the south east side of the rock, shows red in witcher sense, has nothing but a key. Then if you cant find the chest its on the north east side of the same rock. The rock im referring to is the big one with the treasure marker on it, right next to birna's rock

[harleyquinrazer]

Where exactly is the rock? I can't match the screenshot location to online maps of Skellige (I don't even know where the dead Birna Bran is chained to either).

I have just one chest I couldn't collect in the Skellige map and it certainly isn't that one. More info on where it is really would help since I don't know what Sund refers to.