This timepiece, launched in 1976 as the 6309-704X, captured several Seiko dive-watch signatures. Note the wide 45mm cushion case. The day/date display. The broad elapsed-time bezel, screw-down crown at four, and black dial with large luminous plots, and a matching super-legible handset. All told, it’s a handsome, functional, and hard-wearing creation that speaks to the power of intentional design. In 2016, Seiko announced a modern iteration with the SRP777. Capturing the same vibe, and spawning myriad iterations, this Prospex SRP diver was quickly nicknamed “Turtle” and it represents one of the absolute best values in dive watches. —James Stacey