How to access contents of directory underneath mounted volume?

Hello,

On a RHEL4 host, I have a mountpoint, /thing, with a SAN volume mounted 
at this mountpoint.

The local volume that contains the mountpoint (i.e. the volume that is 
mounted at /) is nearly full, and I'm suspecting it is because there are 
files on the local volume in the /thing directory. Of course, I can't 
get to the /thing directory by normal means (at least AFAIK), because 
there is currently a volume mounted at that mountpoint.

Does anyone know if it possible to access (i.e. see and delete) the 
files in the /thing directory without having to umount the SAN volume 
that is mounted at /thing?

Thanks,
Guy.