| Tag | tag |
| Tauchertechnik | diving technology |
| Taupunkt | dew point |
| Technische Unterlagen | technical documentation |
| Teilkörperschutz | partial body protection |
| Telemetrie | telemetry |
| Temperatur | temperature |
| Temperaturanzeige | temperature display |
| Temperaturbeständigkeit | resistance to temperature |
| Temperaturprüfung | temperature test |
| Temperaturschwellenwarnung | temperature threshold warning |
| Tenside | tensides |
| Thrombozyten | thrombozyt |
| Totmannmelder (Bewegungsmelder) | motion distress unit |
| Totraum | dead space |
| Trageband | carrying strap (neck strap) |
| Tragegestell | carrying frame |
| Trägermaterial | base material |
| Tragevorrichtung | body harness |
| Tragezeitbegrenzung | limitation of wearing period |
| Training – heißes | training, hot |
| Transponder | transponder |
| Transport – Blutgase | transport of blood gas |
| Transportbeständigkeit trennbarer Filter | transport resistance separable filter |
| Trennung von Funkkanälen | selection of radio channels |
| Truppführer | squad leader |
| Toxine | toxins |
| T-Stück | T-piece |
| turbulente Luftströmung | turbulent air flow |
| Typschild | type identifying mark |
