You cannot open a .7z file with the default Windows "Extract All" tool. You will need a dedicated archiver.

Because large archives can sometimes be corrupted during download, it is wise to "test" the file before extraction. In the 7-Zip interface, highlight the file and click the button. This ensures every byte of the Guam data is intact before you begin processing. Managing Large Guam Datasets

The official 7-Zip Open Source Utility is the gold standard. For macOS: Use The Unarchiver or Keka .

Unlocking "sandyguam.7z": A Guide to Accessing and Managing Your Guam Dataset