Water proof refurb watch

Since wearing a watch while on water skis would be virtually useless, I wouldn't take the chance personally. It's your money. And when you say about half say it's safe, Apple says it's NOT as I posted above, which came from Apple directly. If it becomes damaged, Apple won't replace or fix the watch, so you'll have to buy a new watch. Your choice of course.

EDIT: I most definitely would never wear a refurbished Apple watch (cased or not) in water. A refurbished watch has been opened and you won't know if the water seal was applied correctly until you get it wet. And if it wasn't, it will be toast.

Your Apple Watch is water resistant, but not waterproof. For example, you can wear and use your Apple Watch during activities such as exercise (exposure to sweat is OK), walking in rain, and washing your hands. For morE info, see:

About Apple Watch water resistance - Apple Support

Please read the link javaliga provided. Contained in the link is this:

What should I avoid while wearing my Apple Watch?

Water resistance isn't a permanent condition and can diminish over time. Apple Watch can't be rechecked or resealed for water resistance. The following can affect the water resistance of your Apple Watch and should be avoided:

• Dropping Apple Watch or subjecting it to other impacts
• Exposing Apple Watch to soap or soapy water (for example, while showering or bathing)
• Exposing Apple Watch to perfume, solvents, detergent, acids or acidic foods, insect repellent, lotions, sunscreen, oil, or hair dye
• Exposing Apple Watch models other than Apple Watch Ultra to high-velocity water (for example, while water skiing)
• Wearing Apple Watch while cliff diving or high diving
• Wearing Apple Watch in a steam room
• Wearing Apple Watch models other than Apple Watch Ultra in a sauna
• Wearing Apple Watch Ultra in a sauna above 55° C (130° F)

Based on this from Apple, I would NOT wear your Apple Watch skiing at all.