law: 4. Use of territorial waters by foreign ships.-
  (1) Without prejudice to the provisions of any other law for the time being in force, all foreign ships (other than warships including sub-marines and other underwater vehicles) shall enjoy the right of innocent passage through the territorial waters.
  Explanation.-For the purposes of this section, passage is innocent so long as it is not prejudicial to the peace, good order or security of India.
  (2) Foreign warships including submarines and other underwater vehicles may enter or pass through the territorial waters after giving prior notice to the Central Government:
  Provided that submarines and other underwater vehicles shall navigate on the surface and show their flag while passing through such waters.
  (3) The Central Government may, if satisfied that it is necessary so to do in the interests of the peace, good order or security of India or any part thereof, suspend, by notification in the Official Gazette, whether absolutely or subject to such exceptions and qualifications as may be specified in the notification, the entry of all or any class of foreign ships into such area of the territorial waters as may be specified in the notification.