A depth charge will go as deep as you set the fuse to pop at.
What was the max depth on the fuse... dunno someone should fill it in.
But say that either you forgot to set the fuse or the fuse was defective therotically the DC would sink untill it hit bottom even if you dropped it in the Mairannas trench.
It is known though that early in the war american crews underestmated the depth that german subs could attain and more often than not set there triggers too shallow.
Generally speaking German U boats could attempt depths much deeper than their allied counterparts.
A balo at over 1,000 feet ... wow thats some lucky SOB's