What a smartwatch water rating allows

Short answer

A rating is a lab pressure test, not a promise for every use. Apple's own footnote says a 50-metre watch suits swimming in a pool or ocean but not scuba diving, waterskiing or other high-velocity water sports, and that resistance can diminish over time.

What the ratings say

Makers rate water resistance in their own vocabulary: metres under ISO 22810, ATM, or an IP code. Each watch page quotes its maker's rating verbatim. Garmin publishes definitions for its ratings, and Apple a support page for its watches; both are linked below.

Apple's footnote on its own spec pages is typical of the limits: a 50-metre watch 'may be used for shallow-water activities like swimming in a pool or ocean' but 'should not be used for scuba diving, waterskiing, or other high-velocity water sports', and 'water resistance is not a permanent condition and can diminish over time.'

Before taking it in a hot tub

A rating describes a pressure test, not every condition a watch meets; none of the ratings quoted here is a hot-water rating. Check the maker's own water page for the model before taking it into hot water or steam, and treat Apple's line that resistance 'can diminish over time' as true of every watch.

Sources

Maker claims quoted on this page are the maker’s own and are labelled as such. This page is general information, not medical advice.

Watches this comes up with

Garmin fēnix 9 smartwatch
Garmin~$1,000

Garmin fēnix 9

Multisport · Garmin

Android; iPhone with limitsPaid tier: Garmin Connect+ECG app, FDA-cleared
smartwatch mode
10 days
always-on display
not published
GPS workout
18 h
  • Topo maps
  • FDA-cleared ECG
  • 29 days (51 mm)

Best for: An athlete who wants the full fēnix map and training stack and does not need satellite messaging

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