| Answer | Crossword Clue |
|---|---|
| sound | to measure the depth of (water) |
| fathoming | Measure the depth of (water) |
| fathoms | A unit of length equal to six feet (approximately 1.8 m), chiefly used in reference to the depth of water |
| unfathomable | (of water or a natural feature) Impossible to measure the extent of |
| impellers | A similar device turned by the flow of water past a ship's hull, used to measure speed or distance traveled |
| impellors | A similar device turned by the flow of water past a ship's hull, used to measure speed or distance traveled |
