Question about Apple Watch Ultra Ocean

Then buy a Garmin, there should be something for everyone.

Garmin is also a sports watch with few smart functions, but excellent sports programmes, while an Applewatch has many very intelligent and very quickly available functions and is also an independent phone. Comparing Apple with Garmin is like comparing apples with pears. I have an Applewatch, as well as a Garmin dive computer and a Garmin Fenix. Everything has its purpose in its time. The office companion is and always will be an Applewatch and the only reason not to buy an Ultra is that I certainly won't be subscribing to a plan for Oceanic's dive computer functionality.

According to Apple, it gives 36 hours with "normal" use and a maximum of 60 hours with minimum power consumption.
Unfortunately, it only works in combination with an iPhone.