Do you mean incrementally?

Yes, zfs send sends the contents that's different between snapshots (or the entire dataset up to a snapshot, if you want).

Hm, I think I understand. So you could save the entire dataset up to snapshot x, then for x+1 you would save just a diff. Might have to play around with this. I currently use ZFS snapshots to protect against accidental data loss and I have daily backups off site but these are managed independently. This might make my life easier.

Yes, zfs send can do both, "the whole thing [up to a snapshot]" and "diffs between snapshots". And it's fast.

Perfect for backups.