NSW Opportunity Class
Unfathomable
adjective/un-FATH-um-uh-bul/
incapable of being fully explored or understood.
In contextThe universe is vast and unfathomable.
Remember it
A fathom measures ocean depth — unfathomable means too deep to measure or understand.
Use it well
Use for mysteries and vastness: 'unfathomable depths/reasons' — grander than 'confusing'.