| Underwater army dangers? | 24 |
| Underwater bloodsucker | 22 |
| Underwater breathing aid | 24 |
| Underwater breathing aids | 25 |
| Underwater breathing gear | 25 |
| Underwater breathing organs | 27 |
| Underwater cave dweller | 23 |
| Underwater concrete depositor | 29 |
| Underwater craft, briefly | 25 |
| Underwater current generator | 28 |
| Underwater detection device | 27 |
| Underwater detection system | 27 |
| Underwater detection systems | 28 |
| Underwater electricity source | 29 |
| Underwater entertainment? | 25 |
| Underwater escape mechanism | 27 |
| Underwater excavation machine | 29 |
| Underwater experiment site | 26 |
| Underwater fishing aid | 22 |
| Underwater forest plant | 23 |
| Underwater hazard marker | 24 |
| Underwater ink squirter | 23 |
| Underwater ink stains? | 22 |
| Underwater lateral surface? | 27 |
| Underwater military guy | 23 |
| Underwater naval habitat | 24 |
| Underwater object locater | 25 |
| Underwater pit residents | 24 |
| Underwater power source? | 24 |
| Underwater research site | 24 |
| Underwater research vessel | 26 |
| Underwater salvager, e.g. | 25 |
| Underwater search device | 24 |
| Underwater search vessel | 24 |
| Underwater sound detectors | 26 |
| Underwater sound device | 23 |
| Underwater transmission | 23 |
| Underwater vessel, briefly | 26 |
| Underwater vessels, for short | 29 |
| Underwater wave generator | 25 |
| Underwater-mine finder, e.g. | 28 |
| Underwater-torpedo inventor | 27 |
| Underwater-tunnel digger | 24 |
| Underway to over there | 22 |
| Underway to over there? | 23 |
| Underway, to Sherlock Holmes | 28 |
| Underwear for the unhinged? | 27 |
| Underwear with underwire | 24 |
| Underweight delivery, maybe | 27 |
| Underwent chemical change | 25 |
| Underwent remission of fever | 28 |
| Underworld code of silence | 26 |
| Underworld meeting place | 24 |
| Underworld money lender | 23 |
| Underworld of Greek mythology | 29 |
| Underworld of mythology | 23 |
| Underworld V.I.P.'s | 23 |
| Underworld, O.T. style | 22 |
| Underwriter's assessment | 28 |
| Underwriter's concern | 25 |
| Underwriters' tasks | 23 |
| Underwriting association | 24 |
| Undeserving of a padded cell | 28 |
| Undesirable alternatives | 24 |
| Undesirable auditorium effect | 29 |
| Undesirable casino companion | 28 |
| Undesirable coastal phenomena | 29 |
| Undesirable consequences | 24 |
| Undesirable engine sound | 24 |
| Undesirable family member | 25 |
| Undesirable part of a record | 28 |
| Undesirable payment status | 26 |
| Undesirable tank level | 22 |
| Undesirable wing coating | 24 |
| Undesired audience reaction | 27 |
| Undeveloped cotton pod | 22 |
| Undeveloped fingerprints | 24 |
| Undid, as an amendment | 22 |
| Undignified command to Fido | 27 |
| Undiluted breakfast drink | 25 |
| Undiluted, as a bar drink | 25 |
| Undiluted, in a whiskey order | 29 |
| Undistinguished emulator | 24 |
| Undistinguished imitator | 24 |
| Undistinguished poet Pound? | 27 |
| Undiversified, as a farm | 24 |
| Undivided, as attention | 23 |
| Undo one's knitting | 23 |
| Undo's menu header | 22 |
| Undoes, as an amendment | 23 |
| Undomesticated, as cats | 23 |
| Undress with one's eyes | 27 |
| Undressed, redundantly | 22 |
| Undrinkable type of cocktail | 28 |
| Undulation in the stands | 24 |
| Unduly high appraisals | 22 |
| Unduplicatable, in a way | 24 |
| Undying belief in jewelry? | 26 |
| Une jeune fille (abbr) | 22 |
| Une ___ (1 a.m., in Paris) | 26 |