PADI vs SDI - What's The Difference?

Jason Burleson   Jan 18, 2024


If you have been researching scuba diving for the first time or know anything about scuba diving, then you've probably heard of PADI, even before you saw the name SDI or it's founding technical diving agency TDI. PADI started over 50 years ago and SDI over 20, so they have been in the market a little longer. In 1999 SDI changed the market for the better in a BIG way!

Before we look into the difference between the two agencies and why Mammoth Dive Academy is choosing SDI over PADI, you should know that when discussing competent agencies in the U.S. alone, it is not just about these two.

There are other agencies that offer similar benefits and have unique advantages.

You may be surprised to know, when it comes to scuba certifying agencies in the U.S. there is a suprisingly large amount of certifying agencies nationwide and just because you're aware of one scuba diving agency more than another, doesn't mean one has less qulaity and less education value. Some might argue that several agencies one-up PADI in certain areas anyway!

When we first opened Mammoth Lake Texas, we were a PADI facility and had an opportunity to stay or bring in another agency. It is actually more work to make a switch to another agency such as SDI, SSI, NASE, NAUI or another worldwide leading agency. But is there is a is worth it!

And for Mammoth Dive Academy there was!

After a proper evaluation, we felt our dive students would benefit more from the SDI training and procedures, so we have invested time and financial resources to move the entire existing staff away from PADI and cross them over to SDI/TDI.

So, What's The Difference Between SDI and PADI?

To be completely fair, there isn't that much! So if they are more alike and differences are subtle, then why invest in the change? Those subtle differences are important and having held certifications with PADI, SDI, NAUI, NASE, and a few others, we feel that SDI is the best choice to serve the diving community. We will break down why we made the decision and investment below.

How SDI and PADI Are Alike - both agencies follow the same global certification requirements, WRSTC.

WRSTC is the World Recreational Scuba Training Council ( and they regulate the minimum standards for all recreational diving courses. These worldwide standards are approved and followed by all leading certifying agencies like PADI, SDI, SSI, NASE, IANTD, RAID and recently NAUI. Member agencies of WRSTC work to ensure there is a minmum expectation of learned skills and consistency in teaching. They collaborate to educate and communicate on behalf of the dive training industry.

Both PADI and SDI have representation on the WRSTC's United States council and they are the ONLY members on the Canadian council as of 2020. WRSTC forms councils to help ensure that all member agencies teaches the same core skills and have commin requirements to become a safe, certified diver.

Certifications Accepted Across The Globe.

Can you dive anywhere? Yes!

Each student receives the same capabilities after their certification, no matter the agency. The agency equivalents of the Open Water course allow students to dive with a buddy, anywhere in the world, up to 60 ft. With any of the top agencies, you can dive anywhere in world.

SDI is recongnized worldwide with more than 24 international offices and thousands of SDI shops. SDI is an active member of the WRSTC and in addition, it's programs are approved by the European Underwater Federation and the International Organization Standardization (ISO). By the way, ISO is not a Scuba thing, it's a worldwide qulaity standard. Perhaps the worldwide standard for ensuring key processes are documented and followed rigorously and their enforsement of SDI is important!

The SDI Advantage

As you can imagine, there are stil lcertain variations between agencies. Our dive has been both PADI and SDI shops and our team has had years of experience with both agencies, so our choice was easy to make. The questions goes to you on how to choose between SDI and PADI?

A Modern Learning Approach

The first decompression tables were developed in 1907. In over 100 years, technology and knowledge continues to advance. SDI chooses to embrace this technology to make diving an even more safer sport for new divers. That's why SDI starts divers with dive computers from day one.

Tables are still important for divers to understand the science behind dive computers and in case their computer dies or fails. But just teaching tables is like handling students in the 2020's an encyclopedia and ignoring the advancements of computers. Or like cars not having airbags. Dive computers not only allow divers to maximize their dive time, they warn divers if they ascend too quickly, if they exceed their no decompression time and how to make decompression stops in the unlikely event they exceed their decompression time.

Dive computers are essential dive equipment!

SDI students learn by using dive computers even as open water students. SDI was the first agency to implement this requirement. In addition, SDI is a renowned leader in eLearning. Their programsare cutting edge and challenging. Don't expect to find any fluffy questions students can blow right through.

You want to learn properly....SDI's eLearning prepares you for the first day of class like no other.

Personalized Experience

Another great plus to being certified by SDI, is they are able to personalize your certification experience. PADI's teaching approach has gained criticism for being too "cookie-cutter."  It's very common for students to struggle with at least one skill during their certification. Fromm PADI's standards, you are unable to move onto another skill until you have successfully completed the previosu skill. This means some students get stuck and even sometimes become overwhelmed with a skill.

SDI allows their instructors to be a bit more flexible and contribute to the success of the student diver. As long as the student completes the skill during the course. they can reorganize the order to allow for divers to become more confident in the water and slowly work up to completing the skill they are struggling with.

This is a HUGE benefit to an instructor and student. And they both appreciate the flexibility.

So How Do I Choose A Scuba Certification Agency


Did you know all the way up to the professional instructor level, you can swap between certification agencies for course? Which means if you've done your open water course with PADI, you can do your advanced with SDI and so on. Although there are a few differences between agencies, they're few and far between.

The Industry Secret

Professionals in the dive community know it's more important to select the right dive shop and staff, than to worry about which agency the shop uses to certify.


Rather than focusing on the agency, focus on the instructor teaching the class. The instructor, size of class and prfessionalism of the shop are going to greatly affect your experience. It's highly possible that you will lover your instructor and proceed through the Open Water Certification with flying colors!!! It is still not a bad idea to ask about the experience of the instructor and ther strengths.

After getting cetified, you will meet many other instructors and can determine who might be a good fit for your continuing education. Some students stay with an instructor their entire career, some bounce around inside the dive shop to take advantage of everyone's combined experience.

Having a string connection with the owners, instructors, retail staff and the dive shop's community is way more important than the logo on your certification card. If you are able to connect with a dive shop and it's community, you have the opportunity to develop life-long, like-minded friends.

In the end the choice is yours and that is why Mammoth Dive Academy offers both SDI and PADI to student divers. Everyone loves options!!