SDI Altitude Diver Course

Lake Pleasant, your regular dive site, sits at about 1,700 feet above sea level. That puts it squarely in altitude diving territory. So do most freshwater dive sites in Utah, Colorado, and New Mexico, many of them between 4,000 and 9,000 feet.

At altitude, atmospheric pressure drops below the sea-level baseline that standard dive tables and many computers are built around. That changes how your body absorbs nitrogen, which changes your no-decompression limits. Diving without accounting for that is not just a certification gap, it is a decompression risk.

The SDI Altitude Diver course covers the physics, the table corrections, computer capability at altitude, gauge correction, hypoxia awareness, and dive planning. It is a focused specialty with a very specific application, and for Arizona divers who want to dive any mountain lake in the region, this is the cert that makes it safe.

What the Course Covers

Why Standard Tables Do Not Apply at Altitude

Standard dive tables are built for sea-level conditions, where atmospheric pressure sits at 1 atmosphere (ATM). At altitude, that pressure is lower. Your body's nitrogen uptake and off-gassing rates shift with it, and sea-level tables underestimate your decompression obligation as a result. The course starts here, with a clear explanation of the physics, before moving into how to correct for it.

Altitude Dive Tables and Cross-Corrections

You'll work through the tables used for altitude planning, including DCIEM and Buhlmann tables, and learn how to apply cross-corrections to United States Navy (USN) tables. The course covers how to calculate no-decompression limits at elevation, how to account for surface intervals between dives at altitude, and how to plan conservatively for travel to higher elevation after diving.

Computers and Gauge Correction

Not all computers handle altitude the same way. Some have a built-in altitude mode. Others need manual adjustment, and some are not suitable for altitude use without additional calculation. Standard depth gauges are calibrated for 1 ATM and will read incorrectly at elevation. The course covers how to assess your computer, how to verify gauge accuracy, and when to use a measured down line if there is any doubt about your readings.

Hypoxia Awareness

Altitude introduces a risk that sea-level diving does not: hypoxia. Reduced oxygen partial pressure at elevation can affect divers before and after a dive, not just underwater. The course covers the physiological effects of altitude on the body, the thresholds where hypoxia becomes a real concern (significant above 4,000 feet), and how to recognize and respond to symptoms.

In-Water Skills

The open water skills component puts the planning into practice. Required skills include:

• Planning a dive at altitude using tables corrected for elevation
• Computing no-decompression limits for the planned dive
• Testing and checking depth gauges, bottom timers, and dive computers before entry
• Executing the dive while monitoring depth and no-decompression time throughout
• Logging the dive with altitude-specific notation

You Are Already Diving at Altitude

Lake Pleasant's surface sits at 1,700 feet, which clears the 1,000-foot threshold where SDI altitude procedures apply. Every dive there is technically an altitude dive. Many Arizona divers do not know that, and it means the Altitude Diver cert is more immediately relevant here than it would be for a diver based at sea level.

Beyond Lake Pleasant, dive sites in Utah, Colorado, and New Mexico regularly sit between 4,000 and 9,000 feet. Without this certification, those sites are off the table. With it, you can plan and execute altitude dives anywhere in the region and know your planning is sound.

Who Can Enroll

The SDI Altitude Diver course is open to certified SDI Open Water Scuba Divers or equivalent, as well as divers currently enrolled in an Open Water course. Minimum age is 10 with parental consent, 18 without. Junior divers ages 10 to 14 must participate in altitude diving activities with a parent, guardian, or dive professional present.

Counts Toward the SDI Advanced Diver Rating

The SDI Altitude Diver certification counts as one specialty credit toward the SDI Advanced Diver Development Program. For Arizona divers building toward Advanced Diver, this is one of the more practical specialties to have in your four, given how often the application shows up on local dive sites.

Gear and Equipment

Students are required to own their own mask, fins, boots, and snorkel for this course. Dive gear rental such as BCD, regulator, computer, tanks, weights, and wetsuit is included in the course. If you'd like to purchase any of your own equipment, we carry a full selection in the shop and all students enrolled in a course receive a discount on purchases during enrollment.

Frequently Asked Questions

Is Lake Pleasant considered altitude diving?

Yes. Lake Pleasant sits at approximately 1,700 feet above sea level, which puts it above the 1,000-foot threshold where SDI altitude procedures apply. Technically, every dive at Lake Pleasant is an altitude dive. Many recreational divers there are unaware of this, which is exactly why the Altitude Diver specialty is worth having if Lake Pleasant is part of your regular rotation.

What is altitude diving in scuba?

Altitude diving refers to any dive conducted at a site above 1,000 feet (300 metres) in elevation. At altitude, lower atmospheric pressure changes how nitrogen is absorbed and released by the body, which means standard sea-level dive tables and many computers need correction to be used safely. The SDI Altitude Diver course covers the planning and skills needed to dive at elevation.

Why do scuba tables change at altitude?

Standard dive tables are calculated for sea-level atmospheric pressure of 1 ATM. At altitude, lower pressure changes the gradient that governs how your body absorbs and releases nitrogen during and after a dive. Using uncorrected sea-level tables at altitude underestimates your decompression obligation and increases the risk of decompression sickness. Altitude-specific tables and cross-corrections account for the reduced pressure at elevation.

Can I use my regular dive computer at altitude?

It depends on your computer. Some models have a built-in altitude mode that adjusts automatically. Others need manual input, and some are not designed for altitude use. The SDI Altitude Diver course covers how to assess your specific computer's capability and how to plan altitude dives when your computer's mode is limited or unavailable.

What altitude requires a specialty certification for diving?

SDI considers any dive site above 1,000 feet (300 metres) to be an altitude dive requiring adjusted planning. Lake Pleasant sits at 1,700 feet. Mountain lakes in Utah, Colorado, and New Mexico commonly sit between 4,000 and 9,000 feet, where the difference from sea-level conditions is substantial.

Does the Altitude Diver certification count toward SDI Advanced Diver?

Yes. The SDI Altitude Diver certification counts as one of the four specialty credits required for the SDI Advanced Diver Development Program.

Ready to Dive Altitude the Right Way?

Contact us to schedule the SDI Altitude Diver course. Call us at (480) 881-4013 or stop by the shop and we will get it on the calendar. We are open Monday through Saturday 11am to 6pm and Sunday 11am to 5pm, at 18618 S 186th Way, Queen Creek, inside The Shooting Range.

For more information and to see course standards, click here!