| Before we have discussed 5 features of a divers | | | | lume pigments marketed under brand names like |
| watch and now we will continue with some more | | | | Super-LumiNova or NoctiLumina and tritium based |
| features. | | | | self-powered lighting devices called "gaseous tritium |
| Pushers | | | | light source" (GTLS) is applied on the dials and |
| Digital and some analog chronograph scuba diving | | | | markers. As for digital diving watches back lights are |
| watch - such as the Breitling Avenger Seawolf | | | | used for low light conditions legibility. |
| Chronograph, Doxa T-Graph, IWC Aquatimer Minute | | | | Power reserve indicator |
| Memory, the Omega Seamaster Professional Chrono | | | | A scuba diving watch with an electric battery |
| Diver series and Sinn U1000 - have specially-designed | | | | powered movement must have an End Of Life (EOL) |
| push pieces that can be operated at depth without | | | | indicator, usually in the form of a jumping second |
| allowing water to enter the case. | | | | hand or a warning message on a digital display to |
| Helium release valve | | | | safeguard against insufficient power reserve during |
| Some scuba diving watches intended for saturation | | | | underwater activities. Some electric and mechanical |
| diving at great depths (typically greater than 100m) | | | | powered movement diving models have power |
| are fitted with a helium or mixed breathing gas | | | | reserve indicators that show the current power |
| release or escape valve to prevent the crystal from | | | | status of the watch. Mechanical movements should |
| being blown off by a pressure build up caused by | | | | be wound or in case of automatic movements given |
| helium that has seeped into the watch in helium | | | | enough motion before a dive. |
| enriched environments as the watch and diver adjust | | | | Crystal |
| to normal atmospheric conditions. Other helium safe | | | | Scuba Diving watches have relatively thick watch |
| for mixed-gas rated diving watches can withstand | | | | crystals face. Sometimes domed crystals are used to |
| the helium used in certain diving situations by using | | | | enhance the pressure resistance of the scuba diving |
| gaskets that simply do not allow helium gas to enter | | | | watch. The typical materials used for crystals are |
| the watch case in a harmful way in the first place. | | | | acrylic glass, hardened glass and (synthetic) sapphire |
| Legibility | | | | which all come with own pros and cons. |
| The dials and markers on the scuba diving watch | | | | * Acrylic glass is very break resistant but can easily |
| face and of course the bezel have to be legible under | | | | be scratched but the small scratches can be buffed |
| water and in low light conditions. An indication that | | | | out with polishing compounds. |
| the watch is running in total darkness also has to be | | | | * Hardened glass is more scratch resistant than |
| present. For easy legibility most diving watches have | | | | acrylic glass and less brittle than sapphire. |
| high contrasting, none cluttered dials and markers | | | | * Sapphire is very scratch resistant but less shatter |
| with a large, easily identifiable minute hand. The | | | | proof than the other crystal options. Anti-reflective |
| markers for 3, 6, 9 and 12 o'clock on the scuba diving | | | | coatings are generally applied on sapphire crystals to |
| watch face and the zero marker on the bezel of | | | | enhance the legibility of the watch. |
| analogue diver's watches are usually conspicuously | | | | Some manufacturers use sapphire/hardened glass |
| styled to prevent disorientation induced read out | | | | laminate crystals, where the scratch resistance |
| errors. For low light conditions luminous | | | | sapphire is combined with the better shatter |
| phosphorescent non-toxic strontium aluminate based | | | | resistance of hardened glass. |