As the PO chrono has wonderful fake screwdown pushers... (yup you cannot unsee it...) So can you use the chrono pushers underwater? The manual makes no reference to this, and the OB gave a not very sure "yes, you can" to this question. And obligatory pic.
Can't see the pic, but yes Omega's Chronodiver watches have pushers that can be used underwater starting with the Seamaster Pro Chronograph 2599.80 in the early 1990s and continuing through to the modern Planet Ocean Chronographs. Its a surprisingly uncommon feature among chronographs really. And while the pushers are not screw down, they are screw in, with multiple seals in them:
Thanks @dsio you caught me in the 30 seconds I was editing the post to include the pic from my phone!
Do keep in mind the seals on yours are probably too old now if they haven't been changed recently so before actually using that feature make sure they're fresh.
The watch went back to Omega about 2 years ago, so the case should be fine just don't use the chrono?
I'd get it pressure tested after 2 years but I tend to be overly cautious, @Archer knows far more than I do about this but for safety I tend to keep my actual swimming watch (usually only 1 out of my collection) pressure tested every year and seal changed every 2, those seals work really well right up until they don't. The $50 I pay every 2 years is far cheaper than the alternative.