Both new Apple Watches swim. Apple rates Series 12 at 50 meters with a depth gauge that stops at 6 meters, and Ultra 4 at 100 meters with recreational scuba certification to 40 meters, and that single difference is what separates a $399 watch from a $799 one in the water.
Everything else in the water story follows from it: the brightness of the screen you have to read through goggles, the hours the battery holds during a long session, and the bands Apple sells for each watch. Here is what Apple publishes, number by number.
Key facts
| Item | Apple Watch Series 12 | Apple Watch Ultra 4 |
|---|---|---|
| Starting price | From $399 | From $799 |
| Water resistance | 50 m, ISO 22810:2010 | 100 m, ISO 22810:2010 |
| Dive rating | None published | EN13319, recreational scuba to 40 m |
| Depth gauge | To 6 m | To 40 m, accuracy plus or minus 1 m |
| Water temperature sensor | Yes | Yes |
| Dust | IP6X | IP6X, plus MIL-STD 810H testing |
| Peak brightness | 2000 nits | 3000 nits |
| Case | 42mm or 46mm, aluminum, titanium or ceramic | 49mm Grade 5 titanium |
What 50 m, 100 m and the two depth gauges mean
Both figures come from the same standard, ISO 22810:2010, and Apple describes the 50 m rating on Series 12 as swimproof. That covers pool and open-water swimming.
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Apple’s wording for Ultra 4 is broader: swim, snorkel, scuba and high-speed water sports. The scuba part is not marketing shorthand, because Apple lists a separate EN13319 certification for recreational diving to 40 meters.
Neither rating is a permanent property. Apple publishes them as ratings on a new watch, and a 50 m watch and a 100 m watch are both sealed against water rather than pressure-tested for you every year.
Series 12 does have a depth gauge, which is easy to miss. Apple lists it in the sensor set alongside a water temperature sensor, and it reads to 6 meters.
Six meters is a snorkeling and shallow free-diving number. Forty meters, with an accuracy Apple states as plus or minus 1 meter, is a recreational scuba number, and it is the reason Ultra 4 sits in a different category rather than a higher tier of the same one.
Both watches read water temperature. Apple has not published a temperature range or accuracy figure for either sensor.
Screen and battery for long sessions
| Measure | Series 12 | Ultra 4 |
|---|---|---|
| Normal use | Up to 24 hours | Up to 50 hours |
| Low Power Mode | Up to 38 hours | Up to 84 hours |
| Outdoor workout | Up to 10 hours | Up to 18 hours |
| Extended workout | Not published | Up to 25 hours |
| 15-minute charge | Up to 12 hours | Up to 18 hours |
| Charge to 80 percent | About 30 minutes | About 45 minutes |
The workout row is the one that matters for a swim camp or a dive day. Ten hours of outdoor workout on Series 12 is 25 percent more than the previous generation managed, and it still ends before Ultra 4’s 18 hours.
Brightness matters more in water than on land, and Ultra 4 peaks at 3000 nits against 2000 on Series 12. Both drop to 1 nit at the other end for a dark room or a night dive surface interval.
Ultra 4 also carries dual-frequency GPS and satellite features, including Emergency SOS, Messages and Find My via satellite, with two years included. Series 12 has precision L1 GPS and no satellite connectivity.
Weight, wrist fit and the bands for water
Ultra 4 weighs 63.0 g in natural titanium and 63.1 g in black, against 32.2 g for a 42mm aluminum Series 12 and 39.5 g for the 46mm. On a swimmer’s wrist that is roughly double.
Fit ranges differ too. Ultra 4 bands cover wrists of 130 to 210 mm, while Series 12 lists 130 to 200 mm at 42mm and 140 to 245 mm at 46mm.
Apple’s water band for Ultra 4 is the Ocean Band, now in a new silicone material in translucent gray, translucent kelp and translucent black. Series 12 launches with Sport Band and Sport Loop colors instead. Apple has not published prices for any of them.
Which one to buy for the pool, the sea or a tank
For lap swimming, triathlon training and open-water sessions inside a couple of hours, Series 12 is rated for all of it, and the $400 you save buys the titanium or ceramic case instead.
For snorkeling past 6 meters, for scuba at all, or for days where the watch has to survive high-speed water sports and then keep tracking overnight, Ultra 4 is the only one of the two Apple rates for the job.
What Apple has not said
Apple has published no swim-specific battery figure for either watch, no accuracy claim for either water temperature sensor, and no extended workout rating for Series 12.
Prices are starting prices only. Apple has not published what the Series 12 titanium and ceramic cases cost, what cellular adds, or what any band costs, and there is no per-model trade-in figure on Apple’s trade-in page.
Both watches went up for pre-order on September 9 and reach stores on Friday, September 18. watchOS 27 arrives first, as a free update on Monday, September 14, alongside the rest of Apple’s September lineup.
