External Drives in Mac OS

In MacOS, external drives are stored in /Volumes   or  {Mac HD}/Volumes

Finder shows the drives on the left of the window;  but /Volumes is the actual location of the external drives in your system.

In most Mixbus file-management windows, you will find a shortcut to "Volumes" on the left; and you can click here to see your mounted drives.

Also note that you can drag a drive folder to the "shortcut" area, and thereby save a link to your favorite drives & folders.