This is not true. If Seiko say it can go 30 m then it can go 30 m. I've dived to 17 m with that particular watch with no issues at all. It's a brilliant little thing, the best value in mechanical watches around.
- Just a small word of warning. This is a great little piece but just be aware of the WR limitations. At 30m it is not recommended to be warn in the shower, while swimming or even fully submerged in water, i.e. dishes, while washing hands etc. Just a concern you should consider before buying this nice little 5.