You dive trimix at those depths. Helium, Nitrogen, Oxygen. Or plain ol' air if you're an animal and enjoy getting narced out of your mind...
I dove the Skycliffe several years ago after my cave diving certification. Crazy story if you all want to hear.
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It's a big ocean, find your own fish
Tuna Time Charters, Boynton Beach, FL
www.TunaTimeFishing.com