How do I backup my data or transfer it to another computer?
From MacDive Wiki
To back up or copy your existing MacDive data, first locate it in your Application Support folder. The full path is:
/Users/your username/Library/Application Support/MacDive/
Note: In OS X 10.7 (Lion), your "Library" folder is hidden by default. There are a couple of ways to access it:
To access this folder:
1. Click on the Finder in your dock.
2. Click on the "Go" menu at the top of your screen.
3. At the bottom of this menu, select "Go to folder.."
4. Paste in the following and press enter: ~/Library/Application Support/
Alternatively, click on the Finder. When your menu bar is showing Finder, you will see a "Go" menu. Hold down alt/option and click on this menu. Select Library from the submenu that appears. This will take you to your Library, and from there you can navigate to Application Support, and then the MacDive folder will be visible.
See also CNET's article for more information/solutions.
From here, you can either back up the whole MacDive directory, or you can open the MacDive directory to selectively back up files (eg, just your data and not your photos). The important file is "MacDive.sqlite" which contains all of your data. You may see other files in here such as original backups of any Dive Log data, photos, etc.
To copy your data to a different computer, you need to copy your MacDive.sqlite data to the new computer. Follow the same instructions, but be aware that if you have never run MacDive you will need to create that directory (New Folder from Finder). Alternatively, you can run MacDive once on the new computer, and then quit. The directory will be made, and you can replace the new (and empty) MacDive.sqlite file with your actual data.