| Clue | Source | Date |
|---|---|---|
| Sound sounds | New York Times | 31 Oct 2024 |
| In certain weather situations, they used to sound warning signals to ships | ||
| Warning devices for ships | ||
| Warning signals for NHS go off | ||
| Ships' warning noises | Eugene Sheffer | 01 Jun 2015 |
| Nautical warnings | ||
| Sounds at sea |