devtrackers.gg
A long while back, I posted this topic after discovering a locked chest that I only happened to stumble upon by chance. That thread was further expanded to show other locations with chests not visible on the map by @bielik01 and eventually an unsatisfactory response on the subject.
Well, today I found another one while letting my raven simply roam, but I discovered it only because Synin spotted a key, not a chest. When going to the location of the key, I discovered this fun moment...
It seems that the key is the key... When exploring the world in Valhalla, go check out any and every key spotted by Synin to make sure there isn’t a locked chest unaccounted for. Still, if the game developers intend for players to find these chests, it would be really helpful if there was some other indicator to show how many unmarked chests there are in the world so that the player can go search for them.