Scuba Diving at Altitude in Colorado: What You Need to Know
Online May 07, 2026
If you learned to dive in Florida or on a tropical vacation, your instructor probably didn't spend much time on altitude. That's because at sea level, the standard dive tables and computer algorithms work exactly as designed.
Colorado is different. Denver sits at 5,280 feet. Chatfield Reservoir is at 5,433 feet. Even the "lower" spots in the Front Range are well above 5,000 feet. That means every dive you do here is an altitude dive, whether you're trained for it or not.
Here's what that actually means for you.
What counts as an altitude dive?
PADI defines altitude diving as any dive above 1,000 feet (300 meters) above sea level. The reason the threshold exists is that standard dive tables and most dive computer defaults are calibrated for sea level conditions. Above 1,000 feet, the ambient pressure is lower than what those calculations assume.
In Colorado, you're starting every dive well above that threshold. You're not doing anything exotic or advanced by diving here, but you do need to understand how the numbers change.
How altitude changes your dive plan
The core issue is decompression. When you breathe compressed air underwater, nitrogen dissolves into your tissues. The rate at which your body off-gasses that nitrogen on the way up depends on the pressure difference between depth and surface. At altitude, that surface pressure is lower than sea level, so your body is working with a smaller pressure gap to off-gas through.
The practical result: at altitude, the same depth carries a slightly higher decompression obligation than it would at sea level. A dive to 60 feet in Colorado demands a bit more care than a dive to 60 feet in Cozumel.
There are two ways to account for this.
Using dive tables. The PADI Altitude Diver tables include a conversion that adjusts your actual depth to a "theoretical sea level equivalent." If you're diving at 5,000 feet and going to 60 feet, you look up a depth of around 70 feet on the standard tables instead. The adjusted number is more conservative and gives you the right no-decompression limits for your conditions.
Using a dive computer. Most modern dive computers have an altitude setting or will detect altitude automatically via a pressure sensor. Before diving in Colorado, check that your computer is set correctly. If it's locked to sea level, it may give you longer no-decompression limits than you should actually use. This is one of the most common mistakes local divers make.
The drive home matters too
Here's something that surprises a lot of people: your decompression obligation doesn't end when you surface. It continues while your body finishes off-gassing over the next several hours.
At sea level, getting in your car and driving doesn't change anything. In Colorado, if you dive at Chatfield and then drive up to Evergreen or Breckenridge afterward, you're ascending to a higher altitude during that off-gassing window. The lower pressure at a higher elevation affects your body the same way ascending too fast underwater would.
The general guidance is to wait at least 12 hours before going above 8,000 feet after a single dive, and longer after multiple dives or deeper dives. Your instructor can walk you through the specifics based on your actual dive profile.
Cold water adds a layer
Colorado's dive sites are cold. Chatfield runs in the low 50s Fahrenheit at depth for most of the year. Cold water slows your circulation, which affects how efficiently your body processes nitrogen. Cold and physical exertion together push your decompression risk up.
This is one of the reasons we push dry suit training for anyone who plans to dive local sites regularly. A dry suit keeps your core temperature up, which matters more than most new divers expect on a 50-degree dive.
What the PADI Altitude Diver course covers
The Altitude Diver specialty is a one-day course. You'll work through the adjusted tables, set up your computer correctly for altitude, plan dives at local conditions, and do two dives at an altitude site.
It's not a difficult course, but it fills a specific gap that most Open Water certifications leave open. If you got certified somewhere with warm, low-altitude water and you plan to dive Colorado seriously, this is the right next step.
The course also pairs well with Enriched Air Nitrox if you want more bottom time, and with Dry Suit Diver if you're planning to dive year-round.
The short version
Diving in Colorado is diving at altitude. That's not a warning, it's just a fact of where we live. Your dive computer needs to be set for it, your dive plan needs to account for it, and your drive home deserves a second of thought.
The good news is that thousands of divers have been doing this in the Denver area for decades without incident. You just need the right training to do it right.
If you have questions about how altitude affects your current certification or whether the Altitude Diver course makes sense for you, stop by or give us a call. We've been diving in Colorado since 1982 and are happy to talk through it.
Underwater Phantaseas is a PADI 5 Star IDC in Lakewood, CO. Call 303-988-6725 or browse specialty courses.
