In the past, if you need to mount an ISO file in Ubuntu, you will have to use an external tool or via the command line. In the recent version of Ubuntu, you can easily mount an ISO directly from Nautilus file manager. Here is how you can do it:
1. Open Files (also known as Nautilus) and navigate to the folder that contains the ISO file.
2. Right click the ISO file and select “Open With -> Disk Image Mounter”.
Your ISO will magically mounted in Files and you will be able to view the content within.
When you are done, simply click the “Eject” icon to unmount it.