A new acoustic tag and process are disclosed for identifying and tracking underwater hosts in up to three dimensions. The acoustic tag has an operation lifetime up to a year or longer at a pulse rate interval of about 15 seconds. The acoustic tag has a signal detection range up to at least about 500 meters that enhances detection probability.
STATEMENT REGARDING RIGHTS TO INVENTION MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with Government support under Contract DE-AC05-76RLO1830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.