HomeBlogBlog100M Water Resistance Explained: What You Can Do

100M Water Resistance Explained: What You Can Do

What does 100M water resistance mean on a watch, and what activities is it suitable for?

“100M water resistance” (also shown as 10 ATM or 10 bar) means the watch case has been tested to withstand pressure equivalent to 100 meters of water under controlled conditions. It’s a durability rating for water exposure, not a promise that the watch is safe for a 100-meter scuba dive.

What 100M (10 ATM) is generally good for

A watch rated to 100 meters is typically suitable for day-to-day water contact and many active situations, including:

Handwashing, rain, and splashes
Showering (as long as the crown is fully secured and you avoid hot water/steam exposure when possible)
Swimming in a pool
Snorkeling near the surface
Water sports with moderate splashing (e.g., kayaking or boating)

What to avoid—even with 100M water resistance

Water resistance can be reduced by heat, age, impacts, or an improperly closed crown/pushers. To protect the seals and prevent leaks, it’s smart to avoid:

Scuba or deep diving unless the watch is specifically certified for diving
Pressing chronograph pushers underwater unless the watch is designed for it
Hot tubs, saunas, and steam rooms (heat can stress gaskets and cause pressure changes)
Strong, direct water jets (e.g., power showers) aimed at the crown or caseback

Practical tips for keeping a 100M watch water-tight

Make sure the crown is pushed in (or screwed down, if applicable) before water exposure. Rinse the watch with fresh water after saltwater or chlorine, then dry it. If you notice fogging under the crystal, have it checked promptly—moisture inside the case can cause permanent damage.

For a deeper breakdown of water ratings and how they apply to a 100M chronograph, visit the full guide here: https://supremechoiceden.shop/guide-steel-quartz-chronograph-watch-men-100m-waterproof/.