I am an Omega man. About 15 years ago when I decided to treat myself to an expensive watch, I chose an Omega Seamaster rather than anything from Rolex, Constantin, Jaeger or whatever. It's rated for 300m, which is 295m deeper than I've ever gone in any of the world's oceans. It's overkill for me, and, I suspect, for 99%+ of people.
But it's a mere amateur compared to Omega's Ultra Deep watch collection. Those watches are rated for 6,000m, which is ludicrous. Very few people have ever gone that deep, and those that have have done so in a pressurised submersible vessel, thus making the talents of the watch irrelevant.
Omega's experimental model of the Ultra Deep accidentally spent two days at the bottom of the of the Mariana Trench, which is nearly 11,000m deep. It survived and had only lost 1 second as a result of the 16,000 pounds per square inch of pressure it endured.
It's a fantastic bit of engineering, but this isn't a watch you buy to go 6,000m down in the ocean. You buy it to go to the pub and regale stories of its depth-wise qualifications. Not that there's anything wrong with that — I never tire of telling people how my hat can survive a journey through an elephant's digestive system. My particular hat hasn't undertaken that expedition, you understand, but the manufacturer claims it could survive it.
If this is the sort of watch you want, it can be yours for a mere £10,060, although there's a waiting list.