A quick warning. On my visit to the keys I quickly went from "swimthroughs" to what I realized had become much closer to penetration. It's pretty easy to get comfortable. I realized that I was beyond my training and equipment when I hit my single 80's valve on the ceiling of a narrow passageway at 100' with a buddy who had an air2. It was a long way from actual wreck penetration (freshly sunk sanitized wreck, some natural light, etc), but it wasn't really "open water" anymore.