page_title: Diving watch
section_title: Legibility
hierarchical_section_title: Diving watch / Characteristics / Legibility
caption_attribution_description: Phosphorescent paint pigment (lume) applied on a Citizen Promaster Eco-Drive BJ8050-08E Diver's 300 m (tool watch suitable for mixed breathing gas diving) to make it readable in low light conditions. The B873 caliber Eco-Drive movement used in this watch can run for 180 days on its secondary power cell before it needs light exposure for recharging.
context_page_description: A diving watch, also commonly referred to as a diver's or dive watch, is a watch designed for underwater diving that features, as a minimum, a water resistance greater than 1.0 MPa, the equivalent of 100 m. The typical diver's watch will have a water resistance of around 200 to 300 m, though modern technology allows the creation of diving watches that can go much deeper. A true contemporary diver's watch is in accordance with the ISO 6425 standard, which defines test standards and features for watches suitable for diving with underwater breathing apparatus in depths of 100 m or more. Watches conforming to ISO 6425 are marked with the word DIVER'S to distinguish ISO 6425 conformant diving watches from watches that might not be suitable for actual scuba diving.
  To a large extent the diver's watch has been superseded by the personal dive computer, which provides an automatically initiated dive timer function along with real-time decompression computation and optionally other functions.
context_section_description: The dials and markers on the watch face and bezel have to be legible under water and in low light conditions. An indication that the watch is running in total darkness also has to be present.
  For easy legibility most diving watches have high contrasting, non-cluttered dials and markers with a large, easily identifiable minute hand. The markers for 3, 6, 9 and (especially) 12 o'clock on the watch face and the zero marker on the bezel of analogue diver's watches are usually conspicuously styled to prevent disorientation induced read out errors. A styling of the hands where no hand can temporarily totally overlay and hence obscure the position of another hand is also desirable to promote constant legibility and prevent read out errors.
  For low light conditions luminous phosphorescent non-toxic strontium aluminate based lume pigments marketed under brand names like Super-LumiNova or NoctiLumina and tritium based self-powered lighting devices called "gaseous tritium light source" (GTLS) are applied on the dials and markers. On digital diving watches, lighted displays are used for legibility under low light conditions.
caption: Lume applied on a diver's watch to make it readable in low light conditions.
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