Innovation in Buoyancy Control
As the field of recreational diving continues to evolve, DAN remains committed to being at the forefront of safety and scientific advancement. The purpose of this article is to educate about a new product gaining popularity on the market. Our goal is to further dive safety while fostering informed discussion and deeper understanding.
If you’ve been traveling or scrolling through dive content recently, you may have come across the Avelo System — a reimagining of buoyancy in scuba diving. No air pockets in a buoyancy control device (BCD)? A full setup weighing only 40 pounds (18 kilograms) compared with the traditional 70? A Hydrotank?
All these new components of the Avelo System are sparking interest while also raising hesitation throughout the dive community. Let’s dive into an overview of this system, highlight its capabilities, and get a quick review of buoyancy and its importance.
What is the Avelo System?
The Avelo System is a new approach to buoyancy and essentially a complete replacement for the traditional open-circuit BCD setup. The system is composed of a Jetpack (similar to a backplate) that houses a pump on the left side, a Hydrotank (available in 8 or 10 liters) in the center, and a battery on the right. The system’s core innovation is eliminating the BCD, thereby removing the buoyancy fluctuations caused by air expansion and compression in the BCD as divers change depth.
In their promotions, Avelo claims to offer the following benefits. This information is from the manufacturer’s website (diveavelo.com) and has not been independently tested.
- Effortless buoyancy control
- Improved air consumption
- Significant reduction in equipment weight and bulkiness
- Increased air capacity (up to 30% more gas capacity)
Similar to the physics of a submarine, the Avelo system, put simply, utilizes a high-pressure, battery-operated pump to flood the tank with water and compress the breathing gas in the Hydrotank to achieve neutral buoyancy.
The design aims to allow gas that would be used for buoyancy control to be used for breathing. This, in combination with a claimed decrease in gas consumption (due to a larger range of neutral buoyancy), is intended to allow for longer dive times.
By simplifying buoyancy control and reducing gas consumption, the Avelo System strives to help divers focus more on the experience — whether that’s underwater photography, scientific tasks, or simply enjoying the dive.
How does the Avelo System work?
Avelo’s Hydrotank is made with carbon fiber and aluminum and contains a rubber bladder filled with breathing gas. At the start of the dive, pressing a button on the Jetpack floods the Hydrotank with water, which compresses the rubber bladder and the breathing gas inside it to further elevate the internal Hydrotank pressure. Replacing gas volume with water allows the diver to achieve neutral buoyancy and begin their descent.
As the dive progresses and gas is consumed, buoyancy increases. The diver can press the button again to flood more water into the Hydrotank and regain neutral buoyancy by increasing the bladder’s pressure once more.
To become positively buoyant (e.g., for ascent), the diver opens a purge valve on the pump, allowing water to exit the Hydrotank and the gas in the rubber bladder to expand. To end the dive, divers swim to the surface and fully open the purge valve, giving the bladder maximal space to expand for positive buoyancy.
Since the pressure of the breathing gas changes significantly when water is pumped into and out of the Hydrotank, breathing-gas consumption is displayed as a percentage of the volume remaining in the bladder rather than by a traditional pressure gauge. Prior to a dive, the amount of weight needed is calculated using a tool on the manufacturer’s website and considers the diver’s height, weight, and exposure protection.
The Avelo interface — called Avelo Mode — is recommended but not required to dive the system. Visit the manufacturer’s website to view compatible dive computers.
If divers do not have the Avelo Mode on their computers, they can reference an Avelo dive slate to determine the turn and return pressures based on the maximum pressure. Maximum pressure is seen on a diver’s submersible pressure gauge (SPG) after they’ve used their pump underwater to gain neutral buoyancy at the beginning of a dive. The system is also certified for use with up to 40% nitrox.
Training and Availability
The Avelo System is currently available to rent at more than 50 locations and on 2-plus liveaboards across the U.S. and 10 other countries, including Bonaire, Mexico, Thailand, and the Maldives.
You must be a certified open-water diver to complete the Recreational Avelo Diver (RAD) course. This course is comprised of an e-learning component and two in-water sessions.
A Quick Review: Dive Physics and Buoyancy
At sea level, we exist under 1 atmosphere (atm) of ambient pressure. As a diver descends, pressure increases by 1 atm every 33 feet (10 meters). According to Boyle’s Law, gas volume decreases in direct proportion to increases in ambient pressure.
This principle is most evident in traditional BCDs, where the volume of enclosed gas expands during ascent and compresses during descent, creating constant buoyancy changes for the diver to manage. In the body, increasing ambient pressure also raises the partial pressure of inhaled gases, causing more inert gas to dissolve into tissues and affecting the volume of gas in nonventilated spaces.
Because BCDs rely on gas volume, their buoyancy characteristics fluctuate with depth changes. In contrast, systems that use rigid or water-based buoyancy chambers — such as those used in submarines and the Avelo System — maintain more stable buoyancy throughout a dive.
Neutral buoyancy is a fundamental dive skill, as abrupt or uncontrolled depth changes can result in injuries such as ear barotrauma or decompression illness (DCI). These risks arise from rapid gas expansion or contraction or from insufficient time for inert gases to safely offgas during ascent. Traditional BCDs, with their variable air pockets, can contribute to these sudden buoyancy shifts and unintended rapid ascents.
By removing the air-filled component of buoyancy control, the Avelo System attempts to minimize these fluctuations. Instead, it promotes more intuitive, stable buoyancy management and significantly reduces the risk of uncontrolled ascent or descent through natural lung control and limited equipment manipulation, providing a smoother and potentially safer dive experience.
Avelo System FAQs
The following responses are based on information from the manufacturer’s website and conversations with the manufacturer.
1. Is a full Avelo setup lighter than a full traditional BCD and aluminum 80 setup? A full Avelo setup is around 40 pounds (18 kg) compared with a BCD and aluminum tank setup that is approximately 70 pounds (32 kg). These numbers depend on an individual’s gear setup and tank(s) used.
2. What happens in case of a failure? Tests of failure scenarios (e.g., constantly running pump, dead battery, or failed bladder) show only minor buoyancy changes, allowing divers to remain at depth with modest swimming effort, in contrast with a traditional BCD in which rapid ascents are more likely.
3. Are you buoyant at the surface with the Avelo System? Divers are at an equivalent height out of the water as they would be with a traditional BCD at the surface when the purge valve is left fully open. Older versions of the system did not support the same surface buoyancy.
4. If you buy an Avelo unit, can you take it on a plane? Yes, typically the Hydrotanks and Jetpack are checked baggage, while the batteries travel in carry-on luggage. You must remove the Hydrotank’s valve prior to the flight. Contact the airline or visit its website for more information and travel rules.
5. Can you dive the Avelo System with a drysuit? Yes, and the system can still offer buoyancy control benefits to drysuit divers.
Final Thoughts
The Avelo System represents an innovative reimagining of buoyancy control in scuba diving. While it offers potential benefits, it also raises important questions about training, safety, and physiological impact.
DAN’s priority is to help the community stay informed and safe. While DAN does not actively endorse any products or technologies, we encourage divers to critically evaluate new technologies and stay current with our latest publications and updates.
Avelo Dive Analysis Tool
The information gathered from the Avelo Mode on a dive computer and gas transmitter during an Avelo dive can be directly uploaded to the dive analysis tool on the manufacturer’s website. This postdive data analysis tool allows divers to view a variety of data points to better understand and evaluate their performance underwater.
The interface allows divers to toggle eight different variables on and off to view how data changes over the course of a dive. Using an algorithm that interprets multiple sensor inputs, the system identifies when the diver was pumping, purging, or making no adjustments to the Hydrotank. Divers can review bladder volume, Hydrotank pressure, air temperature, and percent of air remaining, all of which are affected by pumping, purging, and air consumption.
Gas consumption is presented as a percentage of total volume rather than in PSI or bar, reflecting the Hydrotank’s unique operation. The tool also displays what Avelo terms “workload,” defined as the rate of gas consumption in liters per minute, equating to the surface air consumption (SAC) rate.
A second graph in the dive analysis tool — the buoyancy diagram — illustrates how positively or negatively buoyant a diver was at any moment relative to their comfortable breathing range, which is calculated from the diver’s tidal volume.
As described on the manufacturer’s website, the buoyancy line is generated using the diver’s initial buoyancy, the mass of gas in the Hydrotank, the bladder volume, and the buoyancy characteristics of the exposure suit at depth. This gives a representation of the net buoyant force acting on the diver throughout the dive.
Divers can identify patterns such as improper weighting, uncontrolled ascents or descents, pump-use habits, and gas consumption trends when using the dive analysis tool. These insights can help divers better understand their dives and improve the quality and safety of their underwater experience.
Read this article online at DAN.org/Alert-Diver to view screenshots of Avelo’s dive analysis tool.
© Alert Diver – Q1 2026