Deepest Dives First?

“When making a series of repetitive dives, always make your deepest dive first. Successive dives should be to the same or shallower depth.”

You learned this in your beginning scuba course — right? The real question is, why were you told this?

• Whether using dive tables or computers, it doesn’t take long to figure out that you get your longest no-deco times (or shortest decompression stops) when making your deepest dives first.
• Somehow, people started assuming that doing so was also safer — even though there is no evidence to suggest that it is or is not.

Even now, most instructors will tell you that making a deep dive following a shallow one “isn’t safe.” If you want to have some fun, ask them to explain why. You’ll either get an “I don’t know,” or “That’s what I’ve read” — or you’ll get pure, unmitigated bullshit. In any event, it will be entertaining.

For an intelligent discussion of so-called “reverse profile” diving, see Steve Barsky’s book, Deeper Sport Diving and Dive Computers. The short version is:

• You get the most bottom time (or shortest deco) by making your deepest dives first.
• Nevertheless, should an opportunity drop into your lap to see something really cool — but doing so will take you deeper than previous dives — don’t sweat it.

There is no evidence to suggest you will be at any more or less risk than if you did it the other way around (Barsky does recommend, however, that you go no more than 40 feet deeper than previous dives).

“Properly weighted divers float at eye level” »

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