Why Every Arizona Dive Is Already an Altitude Dive

You logged your Open Water checkout dives at Lake Pleasant, checked your no-decompression limits against a table or a computer, and never thought twice about where you were standing while you did it. Here's the number that changes that: Lake Pleasant sits at roughly 1,700 feet above sea level, and Phoenix itself sits around 1,100 feet. If you learned to dive here, you learned to dive above sea level, and the tables and computer habits built for the coast don't automatically carry over.

The 1,000-Foot Line Most New Divers Never Hear About

Sport diving physics is built around sea-level pressure, one atmosphere pushing down on the surface of the water. Climb in elevation and that pressure drops, and once you're above roughly 1,000 feet, standard sea-level dive tables start reading wrong. Your body absorbs and releases nitrogen differently, your depth gauge reads differently, and a dive computer set for sea level can hand you numbers that don't match the water you're in. Lake Pleasant clears that 1,000-foot line by 700 feet before you even gear up.

Your Computer May Not Be Correcting for This

Plenty of modern dive computers include an altitude mode, and some switch into it on their own. Others need you to set it manually, and a few older models or basic gauges don't account for elevation at all. If you're diving off a table instead of a computer, or you're not sure whether your computer made the switch, you're planning a sea-level dive in mountain water. That gap is exactly what the SDI Altitude Diver course closes.

What the Course Covers

This one's a classroom course. No pool session, no open water dive, no gear to rent or buy, just an evening of the planning knowledge that makes altitude diving safe. You'll learn about altitude tables like DCIEM and Bühlmann, the cross corrections back to standard USN tables, and how to correct a depth gauge and computer for elevation. You'll also cover hypoxia and the altitude bands that matter for planning, from 1,000 feet up past 4,000. By the end, you can build an altitude dive plan from the ground up instead of assuming your gear already handled it.

It's open to certified Open Water divers, or anyone still finishing that certification, age 18 or 10 with a parent's consent. And it counts as one specialty credit toward your SDI Advanced Diver rating, so the evening you spend on it isn't a detour from your training. It's part of it.

Who Needs This Course

If every certification dive you've ever made has been at Lake Pleasant, this applies to you, whether you've thought about it or not. It matters even more if you're planning to dive Arizona's other high-desert lakes, or if your next trip is to a mountain destination somewhere other than the coast, a Colorado reservoir, a Sierra Nevada lake, anywhere the water sits meaningfully above sea level. The specific numbers change from lake to lake. The planning method you learn in this course doesn't.

Training Above Sea Level Is Standard Here

Most dive shops never have to think about this. Their nearest water is the ocean, so their students never touch a table that needs correcting. Arizona doesn't have that luxury, and it turns out we don't need it. Training at elevation means our divers leave already comfortable with a skill that catches people off guard the first time they dive a mountain lake somewhere else, and that's one more reason a certification earned at Arizona's lakes holds up anywhere you take it.

Book the Altitude Course

If you've been diving here for a while and never taken this course, or you're newly certified and want to understand the water you trained in, call the shop and we'll get you into the next Altitude class. It pairs naturally with a Night/Limited Visibility specialty if you're building out your Advanced Diver rating, since both are regular offerings at Lake Pleasant.

Call (480) 881-4013 or visit us to get scheduled, and if you're planning a trip somewhere higher than the coast, check our upcoming trips before you go.

Frequently Asked Questions

Is Lake Pleasant considered high altitude for diving?

Yes. It sits at roughly 1,700 feet above sea level, well past the roughly 1,000-foot point where standard sea-level dive tables stop applying correctly.

Will my dive computer automatically correct for altitude?

Many modern computers include an altitude mode and some switch into it on their own, but not all of them do, and older models or basic gauges often don't account for elevation at all. Knowing how to check and correct manually is exactly what this course teaches.

Do I have to take the Altitude specialty to dive locally?

No, it isn't required to dive many of Arizona's lakes as a certified diver. It's highly recommended, though, since certain lakes do sit at altitude, and it still counts as one specialty credit toward the Advanced Diver rating.

What changes about the physics at elevation?

The surface pressure is lower than it is at sea level. That changes how nitrogen absorbs into and releases from your body during a dive, which is why altitude tables and corrected computer settings exist in the first place.

Are there any pool or open water dives in this course?

No. It's a classroom-only course, so there's no gear to rent and no dives required. You come away with the planning knowledge, not additional dive time.

What are the prerequisites?

A certified Open Water diver, or someone currently enrolled in Open Water, can take this course. Minimum age is 18, or 10 with parental consent.

Does this knowledge apply anywhere besides Arizona?

Yes. Any lake or dive site meaningfully above sea level changes your tables and computer readings the same way. The specific numbers differ by location, but the planning method is the same wherever you go.

Written by Amanda Krugen, SDI Instructor Trainer and TDI Instructor at Dive Arizona.