Australia's Future Orca Interim Submarines

A Boeing, SSN builder HII and US Navy developed Orca unmanned submarine being launched on April 28, 2022. In version above it displaces 80+ tonnes and, with a 7,000nm range, it is a substantial vessel. (Photo courtesy Boeing, via Naval News). 

Orcas have various propulsion options including fuel-cell or diesel powering batteries. Perhaps, in future, they can even be powered by a micro reactor. 

Orcas have many of the capabilities of a manned submarine including intelligence collection, eg. electronic interception and can tow sonar arrays. Orcas can report back to base * via technologies including short range acoustic signals to AUKUS fixed seafloor sensors, aided by Orcas' ability to dive much deeper than manned submarines.

Orcas can lay mines and can be configured (on remote human command) to launch heavyweight torpedoes and anti-ship missiles. The only thing they can't do is special forces/diver delivery.  

* This is noting that in the only modern Western example, HMS Conqueror's sinking of

General Belgrano in 1982, submarines do report back to base before torpedoing a vessel.

HistoryNet records:

“…Conqueror duly reported its change of direction to London at 1400 Zulu. Then, despite problems with its communications equipment, at 1710 Zulu the British submarine received and acknowledged the new ROE and orders to attack. At the same time Cmdr. Chris Wreford-Brown, Conqueror’s captain, transmitted his intention to strike the enemy..."