Best October Prime Day smartwatch and fitness tracker deals in 2025: Save on Apple, Garmin, and Samsung

October Prime Day is almost here -- again. Amazon's annual sale is now semi-annual, with the next one taking place tomorrow. This event is officially called Prime Big Deal Days and lasts for two days. 

We can expect Amazon to cut prices on its company-owned brands, such as Kindle, Ring, and Alexa devices, during this sales event. But more retailers, including Apple, Samsung, Oura, Google, and Garmin, also slash prices on their smartwatches and health trackers to participate. This makes October Prime Day a great opportunity to buy a wishlist item you've been putting off or complete your holiday shopping early. 

Also: The best October Prime Day deals live now

I'm rounding up some of the best smartwatch and fitness tracker deals on sale during October Prime Day. I'm only including products I have either tested myself or that a ZDNET colleague has tested and recommended, because ...