If you are passed class 12th & interested in Indian Navy, You can apply for NDA Entrance Exam. It consists of written examination conducted by the UPSC followed by conduct of the SSB interview, medical test by Indian Navy (naval candidates only) and final preparation of merit list by UPSC.

You can check the further information with the given below link.

https://competition.careers360.com/exams/nda

You can also join  the prestigious Indian Naval Academy, Ezhimala, Kerala for a four years degree course under the 10+2 (B Tech) Cadet Entry Scheme, In order to take admission you need to appear JEE Main Entrance Exam. The Candidates will be called for SSB Interview on the basis off JEE All India rank. You can check the complete information withthe given below link.

https://www.joinindiannavy.gov.in/files/event_attachments/10701-11-0015-1718,10+2,%20B.Tech(Eng).pdf

Good Luck!