Seiko’s first range of truly submersible sports watches came in the form of the Seikomatic 50m SilverWave in 1961, which marked a number of firsts for Seiko – it represented the Japanese company’s first dive watch; their first watch with an inner rotating countdown bezel; their first use of the tsunami wave symbol; and it was their first automatic watch with a screw-down case back.
 
Fast forward to the ever more refined full-serviced 1976 Seiko 6306-8000 SilverWave automatic diver here, which has lost some of the early diver’s rough edges yet retained all (and then some) of the charm.
 
As for the Seiko 6306 diver itself?  Between 1965 and 1975, Seiko brilliantly conceived, designed, and produced three generations of classic ISO-certified 150 m divers’ watches, in chronological order - the 62MAS, 6105-8000/9, and the 6105-8010/9. 
 
Then 1976 arrived...
 
That year, Seiko debuted its replacement for its 6105, conceived in two different specifications - one of which was the 6306 for the domestic Japanese Domestic Market and the 6309 for the international market; the JDM variant - the Calibre 6306 - was fitted with a more advanced 21 jewel 6306A movement, with hacking and an English/Kanji Japanese day wheel.
 
The 6306 lived a rather short life in between the 6105 and down-jeweled and less complex 6309, and was produced from 1976 to 1981, when Seiko would favor the 6309 until it too was replaced with the 7002 diver in 1988.  The 6306 calibre was a successful effort by Seiko to improve the 6105 movement, which allowed for greater lifespan, robustness, and ease of maintenance.
 
As for the Seiko SilverWave line?  Per Fratello’s resident Seiko guru Michael Stockton, “...the mid 1960’s [the era of Seiko's original SilverWave watch, the J12082] were a time of tremendous transition.  It seemed to be a period of transition away from the feel good, somewhat old-fashioned 1950’s into a more modern, but realistic period."
 
"Literature, music, art, and technology were all undergoing these same patterns of metamorphoses…California and its surfing culture went mainstream and people became highly interested in all things water or ocean related.”
 
Seiko’s “sport divers” would become a long-running theme in their watch design that continues to this day. Clearly its SilverWave line were not designed for deep sea / Jacque Cousteau-like dives.  At the time, the only really hardcore dive watches were Rolex, Omega, Blancpain, and some limited others.  But as noted, water sports during this era became mainstream, and the SilverWave line was designed for snorkeling, swimming, surfing, and other light water sports.
 
This Seiko 6306 automatic diver comes on a vintage stainless-steel diver bracelet, and with nylon strap, rugged travel case, and springbar tool.