macOS Mojave local snapshots
Mojave stores Time Machine snapshots as APFS snapshots.

You can list these snapshots using tmutil:

% tmutil listLocalSnapshots /
[…]
com.apple.TimeMachine.2018-12-04-123456


These snapshots are not exposed anywhere in the filesystem by default, but they can be mounted manually using mount_apfs:

% sudo mkdir /Volumes/snap
% sudo mount_apfs -o ro -s com.apple.TimeMachine.2018-12-04-123456 / /Volumes/snap


Make sure to unmount the snapshot when you are done with it:

% sudo umount -f /Volumes/snap