The diver went into the deep water beyond the danger limit.
潜水员下潜到超过危险线的深水中去了。
《新英汉大辞典》
2
And Kai, you are a deep-sea diver.
凯，你是一位深海潜水员。
3
I mean it's the color of night, it's the color of the ocean and as a scuba diver I've spent a lot of time looking into the deep blue, the pelagic blue.