Seiko Prospex

Men's "Marine Green" GMT 42mm Watch

The Seiko Prospex SPB381J1 is a modern re-interpretation of the iconic 1968 Diver’s watch, inspired by Japan’s first hi-beat one-piece diver created by Seiko. The original model’s success laid the foundations for over sixty years of Seiko diver’s watch innovation, delivering precise and wearable timepieces trusted by both professional and recreational divers.

Powered by the new in-house Calibre 6R54, this watch is the first Seiko diver to feature mechanical GMT functionality. Designed for everyday comfort and long-term durability, it offers a bracelet with a low centre of gravity and short-pitch construction, a three-day power reserve, and a high-quality scratch-resistant Japanese ceramic diving scale, with water resistance up to 200 metres.

Part of the Prospex range—combining ‘Professional’ and ‘Specifications’—the SPB381J1 is built to meet the demands of extreme environments while remaining practical and reliable for daily wear. This exceptional timepiece has also been nominated for the 2023 GPHG Awards in the Challenge category, a prestigious recognition from the Grand Prix d’Horlogerie de Genève, celebrating excellence in global watchmaking.

If you’re near one of our stores in Coventry or Loughborough, you’re very welcome to collect your online order in person. Simply give our customer service team a call on 0800 977 4391 and we’ll make sure everything is ready for you when you arrive.

If you’re not local, or just short on time, we offer a range of delivery options to suit you. We have partnered with DHL, DPD & Royal Mail, options include free UK delivery services on orders over £75.00, to express delivery options to most destinations worldwide. All delivery options (excluding 2nd class) are fully tracked and insured for your peace of mind.

Read our Delivery Information page (opens in new window) for a list of all delivery options.

We want you to be completely satisfied with your purchase. If for any reason you are not, you may return your order within the periods below for a full refund or exchange; T&C's apply.

Not Wanted, Wrong or Arrived Damaged
30 DAYS

Orders with Optional Insurance
14 DAYS

For full details please visit our Returns & Exchanges page (opens in new window).

We offer professional engraving on a range of items with precision and care. Whether you’re personalising a gift or adding a special message, we can help bring your idea to life.

Please visit our Engraving page for full details (opens in new window).