For anyone who appreciates a mechanical heartbeat, the Marathon JDD WW194021SS-0110 is a rewarding watch to live with. This 46mm Jumbo Day/Date pairs a Swiss Sellita SW220 automatic movement with a black dial and a stainless steel bracelet.

The SW220 is a self-winding day-date calibre that charges as you move, so there is no battery to replace. It runs on 26 jewels, is protected by Incabloc shock absorbers and holds about 41 hours of power reserve, enough to sit on a nightstand over a weekend without stopping. Setting both the day and date takes only a moment, and the day wheel offers English or French, a nod to Marathon's bilingual Canadian heritage. The sweep of the seconds hand is a quiet pleasure the first time you notice it.

Wrapped around that movement is a genuine search and rescue diver. The 316L stainless steel case is 46mm wide and 18mm thick, with crown guards shielding the screw-down crown and 30 ATM of water resistance. A domed sapphire crystal sits above the black dial, where tritium gas tubes on the markers and hands provide constant illumination. The 120-click unidirectional bezel is oversized for gloved use and carries a MaraGlo pip. Assembled in La Chaux-de-Fonds, Switzerland, and designed in Canada, the JDD wears with confidence on its steel bracelet.

Inside the Marathon JDD WW194021SS-0110

• Reference: WW194021SS-0110
• Movement: Swiss Sellita SW220 self-winding day-date, 26 jewels, ~41 hours
• Case: 46mm 316L stainless steel, 18mm thick
• Water resistance: 30 ATM (300m)
• Crown: screw-down, guarded
• Crystal: domed sapphire
• Bezel: 60-minute unidirectional with 120 clicks
• Lume: tritium plus MaraGlo bezel pip
• Dial and bracelet: black dial, bilingual day; stainless steel bracelet, 22mm

Mechanical, Swiss and built to outlast the trends.