Submarine steel and no nonsense
By Tom Hargreaves, Falmouth, Cornwall ยท
Hull steel. That's the U1's whole pitch, and Sinn are about as German as watch brands get, so there's no marketing waffle around it. The U1's case is made from the same kind of steel used for German submarine hulls, which is very hard and resistant to salt water. It's been tested and certified by DNV to German and European diving standards for 1,000 m. That's an outside body checking the numbers, which I like.
The case is 44 mm and 14.5 mm thick. Big, but the lugs are short so it wears a bit smaller than you'd fear. 22 mm lugs, closed back, screw crown with guards. The bezel is captive, meaning it's fixed to the case with screws so it can't pop off if you smack it against something. I've seen a bezel come off a cheap diver after one hard knock against a boat cleat and that's a horrible thing to lose mid-dive.
Inside, a Sellita SW200-1. 38 hours. Bog-standard, easy to service, you won't care if something goes wrong because any decent watchmaker can fix it.
Here's the gripe. The look is blocky and a bit dated now, and the whole thing feels heavier on the wrist than the U50. And 38 hours for $2,690 to $2,990 is short in 2026 when Tudor and Oris give you two or three times that.
Still, I'd trust a U1 more than most watches on this list. If you want a big tough diver that'll take a battering and you don't care about looking flash, buy one.