You might want to think twice before jumping into the shower with your new Apple Watch Series 9. This may come as a surprise, but smartwatch water-resistance ratings are not very accurate. This may come as a surprise, but smartwatch water resistance ratings are not very accurate.

Okay, so you've got your shiny new Apple Watch SE, and it's water resistant to 50 meters, so you should be fine for any water-based activity. Yes, it is. Well, not really.

Water resistance is determined by how much atmospheric pressure the device can withstand in a short period of time. By the way, 50 meters is equivalent to 5 atmospheres, or 5 times atmospheric pressure; 100 meters is equivalent to 10 atmospheres, 200 meters is equivalent to 20 atmospheres, and so on.

Indeed, the Apple Watch is rated to withstand a depth of 50 meters for a short period of time, but we are talking about minutes, not days. Even a few minutes at this depth places considerable stress on the device's waterproof gaskets and seals.

So no, it's not a good idea to scuba dive with the Apple Watch SE. And while a short swim is fine, you don't want to spend an entire day underwater with the Apple Watch SE on.

What about smartwatches with ratings higher (or lower) than 5 ATM? Below is an explanation of what the most common water resistance standards actually equate to.

3ATM, or 30 meters, tends to be the lowest water resistance rating, at least for smartwatches from reputable manufacturers.

Devices of this grade can be worn while working out or otherwise exercising. They can also be worn while gardening or washing dishes. However, one should avoid swimming with a device that is water resistant to 30 meters, even if only for a short time.

Many of the best smartwatches and best fitness trackers fall into this category, including the Fitbit Charge 6, Apple Watch SE 2022, and Samsung Galaxy Watch 6.

The 5ATM water resistance rating means that your device can swim at surface level for short periods of time. For example, Apple recommends that the latest Apple Watch Series 9 not be immersed in water for more than 30 minutes while wearing it.

By all means, bring your 5ATM-standard device to the beach and enjoy your time playing in the waves, but if you plan on surfing all day, you may want to choose a different wearable.

You also don't have to worry about your 50m waterproof device getting wet while washing dishes, the car, or the dog.

Some high-end smartwatches and trackers, such as the Apple Watch Ultra series and the Garmin Descent MK2, are water resistant to 100 meters.

Devices with this water resistance can be safely worn in wet areas for extended periods of time. This makes it easy to go snorkeling, water skiing, or free diving.

For the Ultra series in particular, Apple says it is also suitable for scuba diving, as it is permitted to be worn to depths of up to 40 meters.

However, there are unfortunately no Coros Vertix 2, although there are a handful, including the G-Shock Move DWH5600 (20 ATM) and the original Coros Vertix (15 ATM).

As for water resistance, it is now in the realm of serious mechanical diver's watches: 15ATM or better water resistance means it can be worn without hesitation in any extreme water activity, including deep sea scuba diving.

Why not explore the Mariana Trench?

Now, no watch can withstand the deepest depths of the ocean, nor can any diver. But if you want to brag to your friends about how your watch is equipped with Jacques Cousteau-level nautical skills, a smartwatch with a water resistance rating of 50 ATM or higher should do the trick.

After all, smartwatches are built to withstand the shocks and splashes of life. And while there are examples of devices that have survived months underwater, they are edge cases and not common.

To get the most out of your purchase and maximize the life of your smartwatch, be sure to follow the guidelines above. If in doubt, remove it.

On top of that, avoid bathing or showering with your smartwatch on, regardless of the smartwatch's waterproof rating. Water vapor is especially harmful to gaskets, and gaskets have a limited lifespan.

Finally, it is recommended to rinse the smartwatch with fresh water after immersion in the ocean or other salty water. This will help avoid corrosion.