Diving within your training: the agencies' limits and the evidence.

What the agencies say

PADI's article on diving restrictions, by Andrew Keaveny (27 February 2024), sets out PADI's general guidance in four parts: that divers not dive alone, stay within their certification level, not dive while impaired, and plan each dive and follow the plan. It adds that some places impose their own extra rules on depth, equipment or insurance, and that these must be followed. How to plan a dive is taught in a course and is not covered here.

A PADI blog by Paula Palomo (published 1 March 2023, updated 30 May 2024) ties depth to training and experience. As PADI describes it, divers build experience within their current limits and take further training before going deeper. Its figures show how a card's limit can depend on what the diver actually did in training:

• Open Water Divers are trained to a maximum of 18 m, or to the deepest depth reached in their training if that was shallower.
• Advanced Open Water Divers are trained to 30 m, or to the depth of their Deep Adventure Dive if that was shallower.
• The Deep Diver specialty prepares divers for dives to 40 m (130 ft), which PADI gives as the recreational limit for air diving without decompression stops. Deeper diving comes under PADI's TecRec technical courses.

PADI's published limits by card

Source: PADI blog, 27 February 2024. Junior limits, and other agencies' figures, are on depth limits by certification.

BSAC: limits on sites and conditions as well as depth

BSAC's Ocean Diver page, which is undated, shows that a card's limits are not only about depth. The qualification covers open-water dives to a maximum of 20 m, from age 12. Two Ocean Divers may dive together under a Dive Manager's supervision, but only at sites they know and in conditions they met in training; new sites and conditions call for a Dive Leader or a higher grade.

BSAC says Ocean Divers can go on to Advanced Ocean Diver, which permits dives to 30 m without decompression stops, or to Sports Diver, which adds deeper dives with decompression stops and rescue training. BSAC's page gives no depth figure for Sports Diver, and the club pages we found disagree with each other, so no figure is given here.

The ISO levels

The international standard ISO 24801 (current parts dated 2014) separates Level 1, the Supervised Diver, who dives under a dive professional's supervision, from Level 2, the Autonomous Diver, the level at which an agency may issue a qualification for diving without a dive professional. Wikipedia (secondary, undated) says most diving organisations recommend that Supervised Divers stay within about 10 to 12 m, and that most do not recommend Autonomous Divers go beyond 18 or 20 m. These are the training bodies' recommendations, not limits written into the standard, whose text was not read for this page.

Where entry-level figures differ

There is no single entry-level depth. PADI gives 18 m for Open Water Diver (2024), BSAC's undated Ocean Diver page gives 20 m for Ocean Diver, and secondary sources give 18 or 20 m for the ISO Autonomous Diver level. Each figure belongs to the body that publishes it, and none is a universal rule.

What the fatality research found

One study looked directly at breaches of safe practice: Shreeves, Buzzacott, Hornsby and Caney (International Maritime Health, 2018). Looking at 122 recreational deaths in North America and the Caribbean, none on training dives, they found:

• breaches of accepted safe diving practice in 45 percent of deaths overall;
• breaches in 75 percent of deaths that were not associated with a medical event, against 23 percent of medical deaths;
• non-medical deaths about seven times as likely to involve a breach (odds ratio 7.3);
• the odds of a non-medical death rising about 60 percent for each extra 10 metres of depth.

The authors recommended following established safe diving practice, along with keeping fit and having regular medical check-ups.

The earlier study by Denoble and colleagues (2008), covering 947 deaths from 1992 to 2003, found the most common triggers were running short of gas (41 percent), entrapment (20 percent) and equipment problems (15 percent). DAN's case files also include deaths on deep wrecks among divers whose certifications could not be confirmed, according to a 2025 InDepth article on DAN's monitoring work.

BSAC's 2024 incident report makes a related point from the other direction: experience and qualifications do not necessarily stop someone becoming a casualty.

Environments with their own training

Some kinds of diving are taught as separate courses. The NSS Cave Diving Section, on an undated course page, describes its Cavern Diver course as a safety and awareness course for open-water divers aged 18 and over, aimed at helping them avoid the mistakes that commonly lead to cavern and cave deaths. DAN's 2010 article on currents, by Mike Ange, says divers should get training before diving in strong current. More on both is on environmental hazards, and the full ladder of cards is on certification levels.