India's ambition to send a team deep into the sea in a submersible vehicle is likely to become a reality in 2021-22 with the Samudrayan project. 

Source: Namasthe Telangana

National Institute of Ocean Technology Director MA Atmanand told NDTV that the idea is to send a submersible vehicle with three people to a depth of about 6,000 metres, to carry out deep underwater studies.

Source: Video Blocks

He added: 

Similar to ISRO's plan to carry persons on a space mission, NIOT has undertaken Samudrayaan. The Rs. 200-crore project proposes to carry three persons in a submersible vehicle to a depth of 6,000 metres under sea. Submarines go only about 200 metres.
Source: Kidshead

According to reports, Samudrayan's success would help India join developed nations in the exploration of oceanic minerals. India has been allocated a site of 75,000 sq km in the Central Indian Ocean Basin by the International Sea Bed Authority for exploration of polymetallic nodules from seabed.

Source: Men's folio

So let's hope the project is on schedule and we too join the big leagues soon.