Marine biology is a scientific discipline which deals with all kinds of sea creatures or marine bodies .
It is a growing field and have a good future . But dear there is a problem .there are not many colleges in india which provides bsc marine biology . The number  of colleges are very less . Also there is less scope in india (however greater demand in other countries ) .however if you have interest then go for it .You can do better in this field .Try to find some colleges in your state . Some colleges are

• Cochin university of science and technology ,kerala
• Andhra pradesh university
• Annamalai university ,Tamilnadu
• College of science and technology,Andhar pradesh
• Veer Narmad south Gujarat university ,Surat

Best of luck