Short diving courses are "madness", an expert has said as inquests were held into diver deaths in the South West.
Mark Jackson learned to dive on a two-week trip to Greece
Dr Philip Bryson, head of the Diving Diseases Research Centre, gave evidence on Tuesday at Plymouth Coroner's Court.
Verdicts of accidental death were given on divers Mark Jackson, of Southwell, Albert Tythecott, of Barnstaple, and Christopher Sidgwick, of Chelmsford.
Dr Philip Bryson said modern diving courses allowed novices to do too much too quickly.
Albert Tythecott, 65, died on one of his first dives off Penzance, Cornwall, in June this year.
The same month, Mr Sidgwick, a 44-year-old builder, drowned despite having a tank full of air while on a dive at the wreck Scylla in Whitsand Bay, East Cornwall.
One year earlier in the same bay, managing director Mark Jackson, 41, from Southwell, near Nottingham, died after a rapid ascent from a dive on another wreck, the James Egan Layne.
He had learned to dive two summers earlier on a two-week trip to Greece and had dived with his son Luke, now aged 17, on trips to Egypt and Florida.
He died when bubbles of air formed in his blood and reached his brain and heart.
Dr Bryson, who specialises in diving accidents, said he was amazed beginners could be certified at advanced level after just eight dives.
He told the inquest into the death of Mr Jackson: "It is madness. End of conversation.
"I have been in this business for 23 years and I do not think someone with 47 dives is an experienced diver. The diving community needs to be totally re-educated."
His comments were echoed by Devon and Cornwall police diver Pc Peter Tapper.
Pc Tapper said: "The whole process moves along far too quickly because there is an element of money. The equipment costs, the courses cost and people try to move along at far too fast a speed."
Plymouth coroner Nigel Meadows said Mr Sidgwick had become confused and it was likely he was breathing air from his smaller back-up tank - which was empty when he was brought to the surface - rather than his main tank which remained full.
Albert Tythcott was diving with another novice and instructor off Lamorna and experienced air supply difficulty while ascending. The cause of death was cerebral arterial gas embolism.
Recording the verdict of accidental death for Mr Jackson, the coroner said: "Diving is a wonderful hobby and it would be wrong for me to discourage it but divers need to be responsible to themselves and to others.
"I only hope that some good comes out of this and this inquest will benefit others."