Knowing how deep to go …

The skilled diver knows how deep to go and calculates his bottom time accordingly while planning for rapidly changing environmental conditions.

Here in Oahu, the task can be as simple as monitoring your bottom timer on a shallow reef dive with 100 foot visibility at slack tide with no current. However,  it can be as hard as a leading a group of 6 divers to a deep shipwreck with ripping currents, limited visibility, and (inevitably) feelings of anxiety coupled by nitrogen narcosis (The rapture of the deep).

I typically run into both situations on a weekly basis.

When deep dives go well
For the experienced diver, deep drift diving, digital photography and EANX work together very well here in Oahu.


Here’s a story:

Last week, when debriefing a shaken-up diver who had run short on air during his deep dive, I explained that he now had a firm grasp on his Personal Depth Limit.

All joking aside, I wasn’t trying to be sarcastic in any way, or meanly criticize the guy.  I simply stated the obvious fact that he now better knew how deep he could comfortably go. This, I explained was doubly useful.

“First, you know yourself and what to expect when going deep,” I said. “Second, you can test your limits and someday go beyond them, if you want.”

The diver then explained to me that his mistake had been in thinking that diving an extra 40 feet past the 60 foot open water mark would be a rather insignificant change.

In retrospect, we agreed that what he failed to do was take in consideration the effects of dissolved nitrogen, increased air consumption with depth, and current.

Nitrogen narcosis: Due to the effects of pressurized N02, I mistakenly overexpose my camera while taking a “prove it” picture of my dive computer at 135 feet.

Narcosis: At 135 feet, I mistakenly overexpose my camera while taking a "prove it" picture of my dive computer.

Putting it all together

When divers master their buoyancy and trim, calculate their Surface Air Consumption Rate (SAC rate), they’re already well on the way to a numerical baseline that helps take the guesswork out of scuba while making it safe and fun.

In the same way, finding and testing your personal depth limit is a crucial skill that can improve a diver’s confidence level by establishing a safe maximum depth.

For scuba divers,  it comes down to what my crazy Divemaster friend Perry says to the girls in Waikiki: “Hey baby, it’s all about your comfort level.”