Diving without a buoyancy compensator and weights – Avelo’s onto something
Scuba diving without a buoyancy compensator or wing – impossible, right? No. Avelo, a start-up from Hawaii, has created a hydrotank with a pump that can take on and release ballast water like a submarine. Recently, the idea won the Innovation Award at the international trade fair «boot».
Aviad Cahana is a diving instructor and engineer certified by several international diving organisations. During his instructing career, novice divers would repeatedly ask him «why’s the equipment so heavy?»
Sound familiar? It does to me. You need a lot of energy to carry the equipment to the water. Anyone who dives from a boat and has to climb back up via a ladder or over the edge of a Zodiac also knows how strenuous this can be in full gear.
For Aviad Cahana, the students’ complaints were the initial spark for his idea. He founded Avelo Labs and from then on worked on a system that weighs less and at the same time makes it easier to buoy underwater. He and his team were awarded the Innovation Award for the Avelo system at boot 2025.
Easier buoyancy and less weight
Traditional diving equipment includes (in simple terms) at least one scuba tank, a buoyancy compensator or a wing with backplate. Since these elements have a lot of volume, a weight system (weight belt or weights in the pockets) is necessary to compensate for the water displacement and to be able to sink.
To control the depth under water, the jacket is continuously filled with air as it sinks. As the pressure increases with every metre, the air’s compressed more and more. In order to maintain the necessary buoyancy, the air in the jacket must be refilled in a well-dosed manner on the descent and released in a controlled manner on the ascent.
Buoyancy control is when you achieve the perfect balance between gravity and buoyancy so that you float stably at the desired depth under water.
Source: Jennifer Idol/Avelo
If you don’t master buoyancy, it’s possible your ascent isn’t controlled and you’ll increase your risk of decompression sickness (website in German). Beginners, in particular, often enter the water with more than enough weight so that they can descend more easily and not shoot to the surface too quickly on the ascent.
If you don’t have the correct buoyancy near the lake or sea floor, you may stir up too much silt or sand. This will impair your visibility and you’ll struggle to get your bearings. Or you’ll accidentally touch corals, spawn or other creatures and disturb their habitat.
How the system works in theory
For Aviad, these were all the more reasons to develop a system that uses non-compressible water instead of compressible breathing gases to regulate buoyancy. He used submarines as a model because they pump water into ballast tanks, which increases the density and causes them to sink. On ascent, water is let out of the tanks to reduce the density.
The Avelo system consists of a lightweight hydrotank and a jetpack, i.e. a pump and battery. According to the manufacturer, this system saves around nine to 14 kilogrammes compared to traditional diving equipment. The Avelo cylinder alone is around 5.5 kilogrammes lighter than traditional steel diving cylinders.
Theoretically, it works like this: divers press a button as they descend, which activates a pump that pumps water into the hydrotank. This makes it possible to descend. Unlike conventional buoyancy control devices, the buoyancy of the hydrotank remains constant and isn’t affected by changes in ambient pressure. This means that neutral buoyancy should be possible at any depth and doesn’t have to be continuously regulated by letting breathing gases in and out. During ascent, it’s the same process, just in the opposite direction.
I haven’t been able to test the Avelo system yet. According to the company, there are currently 31 Avelo Dive Centers worldwide. As a training organisation, Avelo offers the advanced course Recreational Avelo Diver (RAD) to teach certified divers how to use the new system. There are now around 900 divers who have been trained with the new system.
Source: Jennifer Idol/Avelo
Stress-free diving for all levels
Avelo’s system is aimed at those who are just starting out with diving but already have their first open-water certifications, as well as professionals. Another target group are specialised divers who rely on neutral buoyancy for underwater photography or filming, for example.
The partnerships with Scubapro and Shearwater should further increase access to the systems and availability in the future.
Diving without a jacket, wing and weights is more streamlined overall and there’s no need for manual fine-tuning so the diving experience should be less stressful and require less breathing gas.
Thanks to the partnership with dive computer manufacturer Shearwater, the newly developed Avelo mode will also be able to provide feedback on divers’ biometric data and their efficiency under water. Shearwater is offering the Avelo mode on the Teric dive computer. This allows you to see the remaining amount of breathing gas in real time and, after your dive, analyse the most important statistics on depth, ascent speed and no-decompression times.
Developer Aviad Cahana hopes to make diving accessible to more people with his new system and future developments. Lighter, intuitive systems should lower the entry barriers for outdoor enthusiasts, enable them to progress faster and dive more safely and easily than before.
Header image: Jennifer Idol / Avelo
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Siri Schubert
Senior Editor
Siri.Schubert@digitecgalaxus.chResearch diver, outdoor guide and SUP instructor – I love being in, on and around water. Lakes, rivers and the ocean are my playgrounds. For a change of perspective, I look at the world from above while trail running or flying drones.
