The IMILAB W12 is a new smartwatch from Xiaomi's ecosystem that has a lot going for it. According to the manufacturer, the W12 is IP68 certified and should last up to 30 days between charges.
https://www.notebookcheck.net/IMILAB-W12-New-smartwatch-from-Xiaomi-s-ecosystem-comes-with-IP68-certification-and-up-to-30-days-of-battery-life.551065.0.html