Accessing directory pertaining to owner fu that is in directory onwed by bar

I seem to be failing at one fundamental concept of linux.

I have a second hard drive, that is mounted at /media/drive1/ and is owned by owner fu. On that drive, the directory database (/media/drive1/database) is owned by owner bar.

Somehow, if I set myself as bar i cannot cd /media/drive1/database (i receive permission denied). I can access it fine as fu. This is also the case if fu and bar are superusers.

In context this is actually an issue of me trying to move the data of a postgres database to a separate drive, and struggling to set the permissions so that postgres can access it.