Seiko Time Sonar 7015-6010

Sonar, in green. And it has never left its tags.

The rivalry between Suwa Seikosha and Daini Seikosha is proof that a little internal pressure can unlock serious creativity. In the 1960s, Daini, or Kameido, was often viewed as the more conservative arm of Seiko, but the rise of the 5 Sports and SpeedTimer lines marked a shift. As competition intensified, so did experimentation, and with it came some of the brand's most distinctive chronographs. If anything, Daini was often the bolder of the two.

The Seiko Time Sonar Ref. 7015-6010, introduced in 1976, feels like one of the final, fully realized expressions of that chapter. Inspired by submarine sonar displays, it features a semi-transparent dial that reveals the calendar disk beneath, creating depth and motion rarely seen in vintage chronographs. Bold black segments at 3 and 9 o'clock organize the branding and day-date, giving it an instrument-panel feel, while a black minute track and angled tachymeter ring frame the design. The smoked display caseback reveals Daini's flyback Cal. 7015A.

Where the orange dial is the better-known Time Sonar, this is the transparent green variant, which leans even further into the sonar-screen idea: it looks less like a watch dial and more like a glowing display on a ship's console.

If you've been following for a while, you might remember the deadstock orange example we sold on its original rubber strap. This one is its green sibling, and it is just as untouched: deadstock, still with its original tags, and on its original signed rubber straps, a rare variant next to the more common bracelet versions. While Seiko revisited the Time Sonar aesthetic in 2022 with the Kosuke Kawamura collaboration models, nothing quite matches the originality of the 7015-6010.

The watch will be serviced once purchased. Please allow 1–2 months for the servicing to be completed before it ships.

Ships from Tokyo, Japan.

Condition report
This Time Sonar is deadstock and in immaculate condition, with only light marks from storage.

The transparent green dial and handset are immaculate.

The original rubber straps are soft, with the light surface blooming typical of this reference.

The watch comes with its original tags.

Specifications
BRAND: Seiko
MODEL: Time Sonar
REFERENCE: 7015-6010
DIAL: Original transparent green dial
CASE MATERIAL: Stainless Steel
CASE DIMENSIONS: 38 x 43 mm diameter, 14mm Height, 18mm Lug Width
CRYSTAL: Mineral glass
CASE BACK: Screw-in Stainless Steel, smoked display
MOVEMENT: Cal.7015A (Self-Winding), flyback chronograph
Manufacturing date: 1970s
Service History: Unknown, will be serviced after purchase
Bracelet/Strap: Original signed rubber straps
Box & Papers: Original tags