Even though it appears to be a wah! I am very boring / bored:
"Modern and future submarine carriers
There are no submarine carriers in use today, but several concepts exist that could provide a design in the future, allowing an attack force to move entirely underwater, attack without warning, and vanish again.
There is/has been a research project for the US navy, in its changes to the Ohio class submarine from SSBNs to SSGNs, to develop a UAV that resides in and launches from one of the tubes; this UAV is supposed to also be recoverable and presumably reusable."