Related Clues:

• Tracking system
• Underwater detection technique
• Submarine sensor
• Detection acronym
• Locating device is on a roll, revealing what's hidden
• One helps to look up translation of prose epic
• Echo-location system
• Submarine's viewer
• Underwater detector
• Underwater detection device
• Echo-sounding device
• Through repeated reflection, it enables one to overlook obstacles
• Undersea sensing system
• Fairies manage tube with mirrors
• Ability like a bat's to fly high without collision, ultimately