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New Tank Lets Scuba Divers Ditch Their BCD

By Scuba Diving Editors | Updated On November 24, 2021
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New Tank Lets Scuba Divers Ditch Their BCD

Avelo has created a scuba tank that weighs less and holds more breathing gas than a standard scuba tank that compensates for buoyancy changes as the diver breathes down the tank, eliminating the need for a BCD.

The Avelo system uses a lightweight hydrotank, which contains an inner bladder for holding air. Using a battery-operated pump, divers maintain neutral buoyancy by adding water to the cylinder. Water fills around the air bladder within the cylinder. Opening the purge valve allows water to leave the tank. This technology mimics the buoyancy controls of a submarine, which takes on and expunges water to change depth.

The hydrotank is positively buoyant, so a diver with only air in the tank will float on the surface. To descend, divers need only to press a button, pumping enough water into the bladder to become neutrally buoyant and swim down. As breathing gas is consumed and the tank becomes more buoyant, the diver can continue to offset the lost gas with water to maintain buoyancy. Avelo says water only needs to be added to the tank, on average, twice during a 50-minute dive. This buoyancy is not affected by depth, so at the end of the dive all the diver needs to do is swim towards the surface. At the surface, water is purged from the hydrotank to regain positive buoyancy.

Avelo button

A battery-powered button is used to add water to the Avelo dive system.

Alexandra Gillespie

“You don’t need weights,” says Aviad Cahana, inventor of the Avelo system. “You simply borrow your weight from the ocean.”

The Avelo system allows divers to achieve neutral buoyancy without needing a BCD or weights. Without the air-pocket created by a BCD, the risk of instability caused by rapid buoyancy changes is eliminated, and because the system borrows water from the ocean to offset the buoyancy of the tank, divers will all ways have the perfect amount of weight for every dive and every stage of the dive. Creators honed the system over more than 1,000 dives in Hawaii with test divers of varying experience levels, from shop owners to those taking an Open Water course.

Avelo harness

The Avelo system straps on like a BCD, but without an air bladder or weight pockets.

Alexandra Gillespie

The Avelo system weights a total of 40 pounds and consists of a hydrotank, battery, pump and regulator. It has a working pressure of 4,350 PSI.

Avelo has created recreational and professional certification programs to train divers on the operation of their new system. It includes online learning and two open-water dives. No retail price has been listed yet, but Avelo says it will be similarly priced to existing recreational open-circuit scuba equipment. Pending manufacturing and supply chain capacity, it is anticipated Avelo will be made available to recreational divers in 2023.

Learn more about the Avelo system at

Avelo try on

A diver tries on the Avelo system with a large tank with the help of Jennifer Idol, the first woman to dive all 50 states and an Avelo's marketing director.

Alexandra Gillespie

CORRECTION: This article initially stated the Avelo system uses its battery-operated pump to expel water. A purge valve is used to eliminate water, not the battery-operated pump, and the article has been corrected to reflect this.