Submarine tech that India wants

Air-independent propulsion mechanism based on fuel cell that India is looking for its P-75I Project needs to be sea proven.

About P-75I project

The P75I project is part of a 30-year submarine building plan that ends in 2030.

As part of this plan, India was to build 24 submarines — 18 conventional submarines and six nuclear-powered submarines (SSNs).
This project envisages the construction of six conventional submarines with better sensors and weapons and the Air Independent Propulsion System (AIP).

Air-independent propulsion (AIP)

AIP is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen.
It can augment or replace the diesel-electric propulsion system of non-nuclear vessels.