Related Clues:
- Echo-sounding system
- Red October detector
- Ping maker
- School-searching tool
- Aid in finding sunken ships
- Fishing-boat accessory
- Sub apparatus
- Ship tracker
- Dolphin sense
- Viewing instrument in a submarine
- Device for detecting objects used in arson
- Device for detecting objects under water with sound waves
- Underwater echo sounder
- Thus one hurried up to get the echo
- Do the fairies manage to get a higher outlook with it?