| AQUALUNG | Underwater breathing apparatus co-invented by 21 Across. (4,4) |
| COUSTEAU | Oceanographer, film-maker and undersea explorer who co-invented the aqualung and converted the minesweeper Calypso into a research vessel (8) |
| HIAWATHA | More lofty by the sound of it, what a shocking poem by 21 (8) |
| CARDGAME | One of the Jacks played in Croke Park by 21 (4,4) |
| PASSWORD | Send message, one maybe stolen by 21 |
| SEAPERCH | Ocean swimmer's physical education assimilated by 21? (3,5) |
| SNORKELS | Underwater breathing devices (8) |
| SCUBA | Self-Contained Underwater Breathing Apparatus (5) |
| SNORKEL | Neither Chris nor Kelly holds underwater breathing apparatus (7) |
| GRILL | Pump last of air into underwater breathing apparatus |
| SYLLABUS | Head of school blinking upset by 21 Across curriculum (8) |
| AQUA | ___-Lung (underwater breathing apparatus) |
| GILLS | Underwater breathing apparatus? |
| GILL | Underwater breathing apparatus |
| MADEWAVES | When Hedy Lamarr co-invented a radio-frequency encryption system, she __ |
| PICASSO | Pablo ___ Spanish painter of The Weeping Woman who also co-invented collage |
| HEDYLAMARR | Austrian/American film actress, 19142000, who also co-invented a guidance system for torpedoes (4,6) |
| SPRY | Floral designer for the coronation of Queen Elizabeth II who also co-invented coronation chicken and penned some 13 books including Come Into the Garden, Cook (4) |
| RHIANNON | Song written by 21, 26 across and a hit for Fleetwood Mac, 27 across (8) |
| SCUBAS | Ship going around Caribbean island gets self-contained underwater breathing apparatuses (6) |
