Related Clues:

• Sub's 'ears'
• Item on a sub
• Echolocation device
• Destroyer detector
• Salvager's system
• Shade of white
• Whale finder
• Navigational aid
• Navigational system
• Source of waves at sea
• Ship salvager's aid
• Antisub device
• Submarine detector
• It hunted for Red October
• Bat's navigation aid