After surfacing, he did not respond to staff on the dive boat. Attempts to revive him were unsuccessful.
Coroner Brandt Shortland found Mr Brown likely died of a cardiac event brought on by his dive, noting that his failure to fully disclose his medical history had placed himself "at serious risk".
Dive Tutukaka required Mr Brown to sign a disclosure form, and to confirm his dive history and experience in person on the day of the dive.
However, Mr Brown did not disclose that he had undergone surgical intervention for his coronary artery disease - including a catheter procedure and the insertion of a stent - just under a decade before the dive.
He was later found to be wearing a medical alert bracelet, warning of his heart condition, at the time of the dive.
Mr Brown also told the company he had completed 70 dives, but only 26 were recorded in his log book.
Dive Tutukaka said they would never have allowed him to dive had he disclosed his medical history.
Police investigating Mr Brown's death found he had exceeded the safe ascent rate on every previous dive logged on his dive computer, which had activated visual and audible warnings.
Coroner Shortland said there was evidence Mr Brown had placed himself at serious risk on more than one occasion, and he accepted police's conclusions about the fatal dive.
"The stresses and strains placed on his body whilst diving has most likely triggered a cardiac event when Mr Brown returned to the surface after almost running out of air and after a rapid and unsafe ascent."
Mr Brown had also misjudged the seriousness of his heart condition.
"Had he disclosed the extent of his coronary heart history he would have been denied the opportunity to dive and may well be still alive today."
Coroner Shortland accepted the recommendations put forward by the police investigator, including tighter diver screening like that in Australia.
The tighter screening would include a diving medical and consultation with a diver or student's GP to identify medical conditions dangerous to diving.
