Tan Seiko 5...cheap, smart and cheerful.

[I D Howe]

No Omega is not an exception. While the diving watches meet specific ISO norms (see the link) the rest of the range uses the traditional, accepted rating.
In short,
This says 200m, and is good for diving, can possibly resist to 200 metres but is not suitable for saturation diving because of lack of helium valve*:



This says 100m, and has been tested to 100 metres without water ingress although it is not a diving watch:



This one is rated to 30 metres and will only tolerate a light sprinkle when you wash your hands:




* you may do without the helium valve if you must: unscrew and pull the crown to let the gaz out as pressure decreases back to normal in the decompression chamber. But the watch is not fully functional during this time

Sorry mate only having a bit of fun, just love me Omega [and Seiko's] thats all!!
Ian.