Apple Watch Series 4 got wet
Apple Watch Series 4 got wet during a swim, now won't perform. Holds minimal battery.
iPhone 7, iOS 12
Question marked as
Watch Series 4 is marketed as being water resistant, though not water proof. Barring degraded or damaged seals, or mechanical damage, Series 4 should tolerate swimming: Swim with your Apple Watch - Apple Support
Unrelated to the dunking, Apple Watch Series 4 (with the original battery) probably needs a replacement battery, if the battery has never been swapped. What’s the battery health? Settings > Battery > Battery Health
If the Watch or its seals were damaged and water infiltrated, you’ll be replacing the watch.
If the battery has degraded and this is not due to water infiltration, Apple offers battery replacement.
Contact Apple Support, and discuss your options.