A Free Ascent - the Last Resort? Part 1: Undercurrent 08/2025

A Free Ascent - the Last Resort? Part 1

are you competent to make a CESA?

from the August, 2025 issue of Undercurrent

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Last year, we asked our readers if they preferred to dive with a buddy or to dive solo, and many responded that if they dived solo, they could always go to the surface if they had a problem. Many believed that buddies would be unable to help if any serious problem arose. (See Undercurrent November 2024 and January 2025.)

The most likely problem would be out of air, either from an unlikely equipment malfunction, failure to plan for adequate air for the dive, or simply ignoring the air pressure readout, before or during the dive.

Without a buddy, being out of air would require a free ascent of what PADI calls "a controlled emergency swimming ascent" -- CESA.

Back in the day, at least through the '80s, and possibly later, many divers being certified were taught how to ascend to the surface on their last breath, while avoiding a lung expansion injury by keeping their airways open so the air in their lungs could escape. Instructors taught their students to whistle, to blow bubbles, or even scream while rising, thereby allowing the expanding air to escape. Some training agencies allowed instructors to let trainees practice this from as deep as 30 feet, using a fixed line and a close physical hand to grab them in case the ascent got out of control.

Ever mindful of negligence claims, these days PADI has its instructors teach CESA by having trainees swim horizontally with their regulator in their mouth and exhale while swimming. It's not realistic, but it's better than nothing, and it's free of the lung expansion risk. Most newly certified divers are released into the world, fully certified but with no real experience of a sudden air-supply loss and the urgent need to get to the surface....

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