Built first and foremost to go underwater, the Marathon TSAR WW194007SS-0030 is a 41mm Swiss quartz diver's watch on a black three-piece rubber strap, the setup most people would choose for actually getting wet. Reference WW194007SS-0030 puts the Tritium Search and Rescue's 300-meter capability on a strap made to live in the water with it.

Think about what matters on a dive. You need an elapsed-time reading you can trust, so the unidirectional 60-minute bezel clicks in 120 firm steps and is oversized for gloved fingers. You need to read it in murky, low-light water, so the hour markers and hands carry tritium gas tubes that glow without ever being charged, with MaraGlo on the bezel pip and seconds hand. You need it sealed, so the crown screws down and sits between guards. And you need it not to stop, which is where the high-torque ETA F06.115 HeavyDrive quartz and its end-of-life battery indicator come in.

The strap is a 3-piece FKM rubber kit made in La Chaux-de-Fonds. FKM rubber resists salt, chlorine and sunscreen better than ordinary silicone, and the three-piece design lets the watch sit flatter and more securely, whether you wear it on bare skin or over a thin wetsuit cuff. Rinse it off after the swim and it is ready for dinner.

TSAR Diver on Rubber: The Details

• Reference WW194007SS-0030, Marathon 41mm TSAR
• Swiss ETA F06.115 HeavyDrive quartz, end-of-life indicator
• 30 ATM water resistance (300m / 1,000ft)
• 316L stainless steel case, about 14mm thick and 48mm lug to lug
• Sapphire crystal; black dial; date at 4:30
• Tritium on markers and main hands, MaraGlo on pip and seconds
• Unidirectional 120-click bezel, screw-down crown with guards
• Black 3-piece FKM rubber strap, 20mm lugs

Strap it on, check your bezel, and descend.