"Tom Swift and the Electronic Hydrolung" by VIctor Appleton II (Tom Swift Jr., Book 18)

Tom Swift Jr. works with the U.S. Navy to recover a downed Jupiter probe missile in the South Atlantic after it is intercepted and knocked down by a hostile foreign power (the Brungarians)
Tom uses an electronic computer program to calculate the exact coordinate location of the sunken missile on the ocean floor near the St. Paul rocks, racing against time before the Brungarians can reach it first.