What is the criteria for getting admission in best marine colleges? What are the fee structure etc
Well IMU is a central University and it conducts the IMU CET you can check the details here https://engineering.careers360.com/articles/imu-cet. The facilities and all are good.
Check the fee here in the brochure. http://www.imu.edu.in/index.php?prod_id=283
The other options are through CUSAT CAT which is another entrance exam conducted by Cochin University of Science & Technology. There are a few marine engineering courses. for details check this https://engineering.careers360.com/articles/cusat-cat
There is Neotia University for which the entry is through WBJEE. Check the details here https://engineering.careers360.com/articles/cusat-cat Eligibility for this is slightly different so please check that.