Each locked uberchest is tied to a lever somewhere on the level in which it appears. It can be opened by pulling that lever. I have yet to run into a chest that could not be opened by a lever. Make sure you explore the entire level.

thank you Shadezguy, i do explore the entire floor before i decend but have not always pulled each lever, gotten some trapped levers more then i would like and tend to advoid unless i could tell that it was a door or teleporter lever type. but guess i will pull them more often, specially if im finding these chests. thanks again.

No problem, I highly recommend leveling up your character before trying what I told you to, considering there are traps around the map. Maybe level up a skill that increases your chances of resisting or reducing damage taken.

my main character i am doing currently (if i die i reload and keep going as i want to see, i will eventually try it on the harder difficulties and with permadeath but for now while i see what there is...) Swords,Dual weild, Burglery, Perception, Golemancy, Blood Mage, and then the Hitchhiker mod skill. I basicly fully explore a level before going down then go down, if i find to many issues i return to previous floor and level up a bit more then try again. I currently got sent to a Level 0 and its pissing me off as the monsters keep spawning and i cannot get very far and cannot get very far, so loving that i have the ability to reload from last save. But i will make it through at some point. Just got to keep going and levelingup to try and beat the monsters and explore this level more. Im glad i have a little room that i can get to and hide from everything to wait and restore life and mana tho i dont use mana much.

A tip for the überchests : when you have found the correct lever, you can see some sort of green stuff oozing from the lid (not sure what that is supposed to be). You can see it on the minimap too. Unfortunately, the minimap icon is the same for unlocked and already open chests.

Really? I don't see the unlocked ones on my minimap