Dive Watch Water Resistance Explained (2026)

The number on the back of a watch is a pressure rating, not a depth you can dive to. "200 m" on a fishing watch and "Diver's 200 m" on a scuba watch mean different things, and the difference decides whether you can wear it on a tank dive or only while you swim and fish.

How we chose: we did not test these watches. Ratings come from Citizen's and Casio's own pages and manuals, and every pick was sold by Amazon.com and in stock on October 1, 2026. Many diver's watches on Amazon, including every Seiko Prospex diver we found, were sold only by third-party resellers that may not carry the maker's warranty, so we left them out.

Four watches and what each rating allows

Prices are Amazon's, as of the time shown, and subject to change. Details

Citizen's scuba ratings are from its BN0151-09L and BN0200-56E pages. The Casio rows are from the Amazon listings, which Amazon.com sells.

What the number on the case means

Citizen's water resistance guide gives the conversion: "1 bar" is equivalent to a pressure of 1 atmosphere and a water depth of 10 m. So 20 bar and 200 m describe the same test pressure.

What that pressure lets you do depends on the category. Citizen says a watch marked "WATER RESIST 20bar" or "WR 200" can be used for work with frequent contact with water, including fishing, and "in free diving and aquatic sports (swimming, yachting, fishing, etc.)." It does not list scuba.

A watch marked "DIVER'S WATCH 200m" or "AIR DIVER'S 200m" is a different class. Citizen describes it as "pressure resistant to the depth indicated and featuring water resistance suitable for long periods of underwater use," and "ideal for both skin diving and scuba diving."

ISO 6425: what makes it a diver's watch

The standard behind that class is ISO 6425. Citizen's guide states that "products classified as diver's watches comply with the ISO6425 standard." That is why we only call a watch a dive watch when its maker says so on the product page.

Both Citizens here carry that claim. Citizen's page for the stainless BN0151-09L calls it an "ISO-certified Promaster Diver" and rates it "200M/20Bar [Scuba Diving]." The titanium BN0200-56E page says "ISO-compliant Super Titanium Promaster Diver" with the same rating.

The Casio Duro shows why the label matters. It has a rotating bezel and 200 m on the case, but Casio's own Amazon listings for the MDV-106 series call it "Diver-Style" and "styled after classic dive watches." That is a look, not a diving rating.

Key point: Casio's WS-1700H user's guide shows its non-diver chart, where 20 bar covers windsurfing and skin diving, and then says: "Do not use your watch for scuba diving or other types of diving that requires air tanks."

Smartwatches use a third label

Garmin rates its watches in ATM rather than meters. Its water rating definitions put 20 ATM at pressure equal to 200 meters, for swimming, snorkeling and high-speed water sports. Only a separate "Dive" rating, "tested to engineering standard EN13319 for dive compliance," covers scuba diving. Our tide watch guide covers the Garmins.

Salt water, rinsing and gaskets

A watch's rating depends on rubber gaskets, and both makers say they wear out. Citizen says gaskets "may lose their elasticity or become brittle" from sweat and moisture, and recommends having them replaced "at least once every 2-3 years." If water gets inside, Citizen says to stop using the watch and send it for repair.

Casio's manual gives the same interval, "about once every two or three years," and says to use plain water to rinse all salt and dirt off after the watch has been in seawater. It adds that a technician should check water resistance whenever the battery is replaced.

Both makers warn against working the crown or buttons while the watch is wet or under water. Rinse the watch with the rest of your gear; our boat and gear wash guide covers the rinse routine.

We found no CPSC recall for Citizen or Casio watches in our recall tracker.

Related: G-Shock vs Garmin Instinct for fishing, saltwater reel care.

Frequently Asked Questions

Can I swim with a 100 m watch?

Yes. Casio's chart allows swimming at 10 bar (100 m), and Garmin lists swimming and snorkeling for 10 ATM. Neither covers scuba diving.

Do Eco-Drive divers ever need a battery?

Citizen says Eco-Drive is "powered by light, any light" and "never needs a battery." The gaskets still need replacing on Citizen's 2 to 3 year schedule.

Is titanium better than steel in salt water?

Citizen says its Super Titanium is rust resistant, five times harder and 40% lighter than stainless steel, per the BN0200-56E listing. Either case still needs a fresh-water rinse for the gaskets and bezel.

Why are there no Seiko divers here?

Every Seiko Prospex diver we found on Amazon on October 1, 2026 was sold by a third-party watch dealer, not Amazon.com or a Seiko store, so we could not confirm the warranty that comes with it.

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SaltProofLab is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Water resistance definitions are quoted from Citizen, Casio and Garmin.