| ECHOSOUNDER | Device for determining the depth of the sea (4,7) |
| SOUNDED | Measured the depth of the sea |
| GULF | From "bosom", a trough between waves; the depth of the sea; an abyss, bay, chasm, whirlpool or other deep place; or, a figurative gap or divide (4) |
| SPIRITLEVEL | Device for determining the horizontal (6, 5) |
| RANGEFINDER | An instrument for determining the distance of an object from the observer (11) |
| BRIDGE | see 1dn, A device for determining the value of an unknown resistance by comparison with a known standard resistance |
| WHEATSTONE | and 6dn,A device for determining the value of an unknown resistance by comparison with a known standard resistance |
| LIEDETECTOR | A device for determining if a person is telling the truth (3,8) |
| INNERSPACE | What one has in mind for the depths of the sea? |
| RADIOCARBON | ___ dating (method of determining the age of an organic object) |
| FINDER | A discoverer; or, a short word for an optical device on a camera for determining the field of view (6) |
| NEREUS | In Greek mythology, a sea god who lived in the depths of the sea with his wife Doris and their daughters |
| CALCULATION | Act of determining the answer to an arithmetical expression (11) |
| POINTS | --- system, a method for determining the winner of a cricket series involving multiple formats of matches (6) |
| HYBRIDISATIONS | Techniques for determining the similarity of two DNA or RNA strands from different sources (14) |
| BCS | System for determining the top NCAA football team |
| ECHO | Device for determining sea depth directly under a vessel, ... sounder |
| ITALIANSUB | Vessel for exploring the depths of the Adriatic Sea? |
| SCRATCHTEST | Exam for determining allergies |
| SOUND | Discover the depth of the noise (5) |
