A few months back Opera 11 installer added portable install option for Windows users, now Mac users’ turn, Opera now supports portable install option for Mac users, which means Mac users can carry their bookmarks, settings, mail and everything with them in their USB drive.
Latest Opera Snapshot for Mac supports the portable installation.
Installing Opera Portable for Mac
1. Download and mount the disk image.
2. Drag Opera from disk image to a USB stick or external drive.
3. Opera Terminal.app and drag Opera from the USB stick drop it on top of the Terminal window.
4. Press backspace once then and type /Contents/MacOS/Opera -createsingleprofile and then press Enter.
Opera 25 Stable features Visual bookmarks, Built-in PDF Viewer and 64-bit (only) Mac Version
No Out-of Process Plugins for Opera 12.10 On Mac
You only have to run this once and it creates a hidden folder /Volumes/volume-name/opera profile/ which contains all the settings, bookmarks, mail and disk cache.
Via [ Opera Desktop team]