Ask anywhere on the internet for a cheap dive watch and you will get two answers within five minutes: the Casio Duro MDV106 and the Invicta Pro Diver 8926OB. They occupy the same price shelf and both have a decade-plus reputation, which makes them look interchangeable. They are not. One is a quartz watch with an original design; the other is a mechanical watch wearing someone else's.
The Duro is a Casio: quartz, 44mm, a real 200m rating, and a design that owes nothing to anyone. The Pro Diver is an Invicta: a Seiko NH35A automatic in a 40mm case that is an unmistakable Rolex Submariner homage. Both are rated 200m. Both are good at what they are. The decision is really about which of two very different things you want.
If you want the most reliable, most accurate cheap watch that can go in the sea, buy the Duro. If you want the cheapest way to own a mechanical automatic watch you can swim with, and the homage styling does not bother you, buy the Pro Diver. If you have a smaller wrist, the 40mm Invicta is the more wearable of the two.
Quartz vs automatic: what you actually notice
The Duro's quartz movement will keep time to within a few seconds a month and asks nothing of you until the battery dies in several years. The Invicta's Seiko NH35A is a mechanical automatic: it winds from your wrist movement, runs for around 40 hours off the wrist, and will drift by anything from a few seconds to half a minute a day. That is normal for a mechanical watch at any price. If accuracy is the goal, quartz wins and it is not close. If the point is to own something with a spinning rotor and a heartbeat, only the Invicta delivers that.
Size: 44mm versus 40mm
The Duro is 44mm across with a 48mm lug-to-lug and 22mm lugs. The Pro Diver is 40mm with 20mm lugs. On a 6.5-inch wrist that is a genuinely large gap — the Invicta is the one that disappears and the Casio is the one people notice. It also affects your strap drawer: 22mm for the Casio puts it with the Seikos, 20mm for the Invicta puts it with the field watches.
Design: original versus homage
This is the part nobody wants to say out loud, so we will. The Invicta Pro Diver is a close copy of the Rolex Submariner, down to the case profile, bezel and bracelet. Some buyers do not care, some actively want it, and some find it embarrassing. There is no technical argument here — just know what you are strapping on. The Casio Duro looks like a Casio, and in fifteen years of being the internet's default cheap watch it has earned its own identity.
Build and quality control
Casio's manufacturing consistency at this price is famously good — the Duro is the same watch every time. Invicta's is more variable; owner reports of bezel alignment and bracelet finishing vary more than they should. Both are cheap enough that the risk is low, but if you want the safer purchase, that is the Casio.
What both of them need
A strap. The stock bracelets on both are the weakest component and the first thing owners replace. That is not a criticism — it is where the manufacturing budget went. A $15 NATO or a quick-release silicone strap makes either watch feel twice its price. Check the widths above, then see our rubber strap picks.
How we picked
We do not run a testing lab
We compiled the published manufacturer specifications for every watch here — case size, lug-to-lug, lug width, water resistance, movement and crystal — did the wrist-fit and value math, and scored each pick against a published rubric. The scores are judgments from documented research — they are not measurements we took or wrist-time we logged, because we do not have these watches and we are not going to pretend we do. Where a spec could not be verified we wrote "data unavailable" rather than guessing.
