How to Share Air While Scuba Diving

Running out of gas underwater is one of the most serious emergencies a diver can face. In that moment, how you respond—and how quickly you can share air—can make all the difference. That’s why it’s critical for every diver to understand how air-sharing works, how their gear is configured, and how to practice it before it’s needed for real.

There are two common ways divers are trained to share air: primary donate and octopus donate. Both are used across different training agencies and equipment setups, and both can work well when executed properly. But they’re not interchangeable—and the method you choose affects how your gear is configured, how you train, and how you respond under stress.

This guide breaks down the differences between these two approaches, explores the pros and cons of each, and offers some thoughts on which method might be best for your diving style and goals.

The Two Main Air Sharing Methods

Primary Donate

• The diver gives their own regulator (the one they’re breathing from) to the out-of-air diver.
• They then switch to a backup regulator secured under their chin with a bungee necklace.
• This method is taught by GUE, technical instructors, and many experienced SDI/SSI professionals.

Octopus Donate

• The diver keeps their own regulator and donates a yellow backup (octopus) that’s clipped to their BCD.
• This method is commonly taught in most Open Water courses from agencies like PADI, SSI, and SDI.

Visualizing the Two Configurations

Primary Donate - Also known as "Long Hose"
Pros:

• Regulator given to buddy is guaranteed to work
• Gear configuration is more streamlined
• Longer hose means you are not up in their face

Cons:

• Requires specific training and gear configuration
• May confuse buddies unfamiliar with the setup

Octopus Donate - Also known as "Standard"
Pros:

• Widely taught and familiar to most new divers
• Regulator never leaves the donors mouth

Cons:

• Octopus may be dangling or difficult to access
• Octopus often neglected during pre-dive checks
• Shorter hose means you are up in their face

Recommendation

We recommend primary donate for divers who want a consistent, high-reliability approach—especially those diving with teammates, pursuing advanced training, or operating in overhead environments. It removes ambiguity in emergencies and ensures the out-of-air diver always receives a functioning regulator immediately.

However, octopus donate still has a place in recreational diving, particularly when using rental gear or diving with buddies trained in that method. If that’s your setup, make sure the octopus is clipped, accessible, and tested before the dive.

The most important thing isn’t which method you use—it’s that you and your buddy agree on it before getting in the water.

Personal Perspective

I personally prefer primary donate. My primary regulator is on a long hose, and my backup is on a bungee necklace under my chin. I don’t have to guess what to give—I just pass the reg I’m breathing and grab my backup. It’s clean, consistent, and easy to execute even when things go sideways.

That said, when diving with new buddies or using rental gear, I’m always ready to switch approaches if needed. Communication before the dive is more important than the method itself—but for long-term consistency, I strongly prefer primary donate.

Pre-Dive Air Sharing Checklist

Regardless of which method you use, it’s critical to talk about it with your buddy before the dive. Here’s a quick checklist to run through:

• What air-sharing method are we using? (Primary donate or octopus donate?)
• Do you know where my backup regulator is located?
• Have both regulators been tested for function and bubbles?
• What’s our minimum reserve gas plan?
• Do you have any air-sharing training or preferences I should know about?

These questions take less than a minute to cover, but they ensure that both divers are on the same page—and that air sharing won’t be a surprise if it’s needed.

What to Do If You're the One Out of Air

It's easy to focus on the donor’s role—but what about the diver who’s out of gas? Here’s what to do:

1. Signal clearly and early. Make strong eye contact and use the standard "out of air" signal.
2. Take the offered regulator—don’t grab. Let your buddy give it to you.
3. Start breathing and calm yourself. Wait for at least one or two steady breaths.
4. Signal “OK” once you’re stable.
5. Begin a controlled ascent with your buddy, staying close and communicating throughout.

Staying calm and executing this sequence cleanly gives both of you the best chance of surfacing safely.

Sharing Air Is About More Than Just Equipment

When an air-sharing emergency happens, it’s not just about which regulator you donate—it’s about how you respond under stress. Panic, confusion, and poor communication are far more dangerous than gear choices.

That’s why practicing these skills in calm, realistic conditions is so important. It builds trust, reinforces clear communication, and reduces hesitation when it matters most. Focus on awareness, coordination, and teamwork—not just the mechanics of handing off a regulator.

Air-sharing isn't just a gear drill—it's a human interaction.

Why Minimum Reserve Gas Matters

One of the best ways to avoid ever needing to share air is to plan your gas reserves properly. That means calculating a minimum reserve gas amount — enough to get both you and your buddy to the surface safely in case one of you runs out of gas at the worst possible point in the dive.