Unintentional Ascent by Student Diver

A novice diver inflated his BC and resulted in an involuntary ascent.

Reported Story

The diver (Diver 1) was an entry-level diver, who started the descent with an instructor and two other student divers. They descended following a mooring line and the group remained close to each other.

A few feet before reaching the bottom, one of the students slowed down her descent. The instructor looked at her, and asked if everything was OK. When he turned around to look at the other two students, he realized one of them (diver 1) was no longer on the descent line. The instructor looked around and realized that diver 1 had surfaced. The instructor ascended to find out what was going on.

Upon reaching surface, the diver was being helped by the boat’s crew, who had just entered the water to initiate their dive. Diver 1 was taken aboard, where he was kept for observation.

Once ensuring that Diver 1 was taken cared of, the instructor resumed the dive with the two other students who were at depth and completed the required exercises and returned to the vessel.

When the instructor talked to Diver 1 later, he said that when he reached the bottom, he inflated his BC which resulted in an involuntary ascent. He said that his ascent was normal as well as his respiration. He replied that he ascended breathing normally.

Diver 1’s computer showed:
• Depth: 4.7 meters (15.5 feet)
• Dive time: 0 minutes
• Ascent rate: 34 meters/min

Diver 1 remained under observation for one hour, repeatedly asked if he was feeling anything unusual, how his breathing was, or if there was anything wrong. All of which he answered to as being normal. When asked again about the ascent, he reiterated he surfaced breathing normally.

Later in the day, Diver 1 returned to the water and completed a dive.

After completing one dive, he seemed visibly concerned with the prior incident and the rapid ascent, but since he reassured the instructor that he was breathing normally during the ascent, and since the bottom time was less than one minute, he was assured by the instructor that everything should be alright but will continue to monitor him.


Accidents happen without notice. Fortunately, there were no severe consequences from this incident. The diver contacted the DAN Hotline and he was encouraged to seek medical evaluation. A mild lung hyperdistension seemed possible.

It would have been prudent to call off the dive operation and transport the diver to a medical facility for evaluation after the accidental ascent. Also, the inopportune activation of his BCD may have been a sign that he is not yet familiar enough with its use and could have benefited from additional instruction. An assistant could have improved student supervision for those who were not under direct supervision of the instructor.

Sergio Viegas, DAN Brasil