hello 

there are colleges offering ocean or marine engineering in b tech while oceanography is mostly offered for bsc and msc. as you have asked for btech the top colleges offering this stream are 

IIT kharagpur

IIT madras 

IMU

HIMT

THE ENTRANCE EXAMS ARE

• Indian Maritime University Common Entrance Test: IMU conducts Common Entrance Test for undergraduate programs in May.
   
• HIMT Online Entrance Test: This test is conducted by HIMT across India.
   
• IIT Joint Entrance Examination: It is the examination conducted for IIT aspirants.                                           hope it helps.