A Masterpiece Symbolizing the History of Dive Watch Development
Seiko, a pioneer in the field, developed Japan's first dive watch in 1965. While the water resistance at the time was 150m, Seiko's current lineup includes high-spec models that achieve saturation diving water resistance to 1000m. These are the "Prospex Marinemaster Professional 1000m" models we introduce today. These remarkable deep-sea models can truly be called masterpieces symbolizing the company's history of dive watch development.

The first domestic dive watch, released in 1965, was used by the 8th Japanese Antarctic Research Expedition overwintering team starting in 1966, and its ability to maintain performance even in extreme cold was widely recognized. Subsequently, in 1968, the second-generation model appeared, achieving 300m water resistance through the adoption of a "one-piece case" with an integrated middle case and case back, and "Hardlex glass" with high hardness. This model was equipped with the high-precision "61 series" movement, boasting 36,000 vibrations per hour, and is also famous for being a favorite of the late legendary mountaineer Naoji Uemura.

Later, in 1975, the third-generation model emerged, achieving 600m water resistance by using a titanium outer shroud with a black hard coating.

The Arrival of Seiko's First "Mechanical 1000m Saturation Dive Model"
By employing Seiko's unique L-shaped gasket, the airtightness inside the watch was enhanced, and helium gas penetration was blocked. This marked the arrival of a true professional-spec dive watch capable of "saturation diving," which professional divers undertake when working in the deep sea. The protector structure using an outer shroud and the L-shaped gasket for saturation diving, adopted in this model, are inherited by current models. However, the 1000m water resistance milestone was reached in 1986, after the adoption of a solid ceramic material for the outer shroud. Following numerous minor changes, the history of Seiko divers continues to the present day. For special watches used underwater, where even minor trouble can lead to immediate life-threatening situations, Seiko has created the ultimate divers' watch, ensuring complete safety.

Since 1978, this model has been equipped with a high-precision quartz movement, but in 2009, an automatic model was introduced. The appearance of Seiko's first "mechanical 1000m saturation dive model" caused excitement among long-time fans.