Well I do not agree with the question firstly.
You need to go to the best Merchant Navy Institute , it should not depend upon location at all . Your priority should be to get into best college ,have the best placement and then move ahead in life . Now if that college is in MUMBAI or Kolkata should not be a reason to change your mind.
Now coming to your point:
For DNS
- AEMA , Karjat( Anglo Eastern Shipping Company)
- Get sponsorship of Companies like Scorpio , Synergy , Wallem’s , V Ships ,Great Eastern.