Dear Ayush, If you want to join merchant navy first you have a background of science stream in 10+2 stream. Candidate should be unmarried.

After 12th there are some specific merchant navy courses like B.Sc Nautical science, marine engineering, Naval architecture and offshore engineering, petroleum engineering etc.

After 12th you have to give IMU CET entrance exam which is compulsory. After clearing cutoff you can join courses.

For more information about IMU CET visit this link https://www.imu.edu.in/

All the best dear have a very bright future ahead.