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Definitely more expensive than lake diving, but not a bad deal when you consider the number of dives and that the liveaboard includes your lodging and food for the time you are away also. Definitely on my U.S. diving bucket list. https://www.texascaribbean.com/You can also go on the MV Fling to the Flower Gardens for a much more enjoyable (and expensive) experience
The Instructor Manual says:I'm guessing some might do that on the MV Fling liveaboard to the Texas Flower Gardens.
BTW, I'm not an instructor, but I seem to remember that the deep dive for PADI AOW only has to be something like over 60 feet (confirmed: Advanced Open Water Diver | PADI). Not sure what depth of dive is required for the Deep specialty. Hopefully one of the instructors on here can chime in on those.