You'll never reach the "perfect dive" ... but this one was close to

http://www.youtube.com/v/biB99PbpsrA;autoplay=1

to make a few thing clear ... this kind of dive on air is not a fundive just between ...

it requires a disciplined deep dive preparation ...
- adaption dives to the depth
- stress management training
- mental training ( breathing technic , visualisation )

in following in brief a few stats to the dive on the video ...

before the dive
- early morning ( quietness at the divesite )
- extra equipment ( deco tank, ect. )
- buddies fit for this dive ?

briefing in points
- no decompression dive
- all signs ( gilliam finger at depth )
- entrance and descending point
- formation during the dive
- 1' breathing immersed on the surface without mask ( diving reflex, visualisation )
- 2' descending to max depth
- 63m max depth ( perfect buoancy )
- 2' no stop time
- speed ascending with stop in 25m ( after 6' dive time back in 25m )
- deco stop simulation in 18/15/12/9/6/and 3m
- surfacing after 33'

and we followed the diveplan nearly perfect ... ;D

exalting risk in a 60m deep dive in blue hole
- bottom is in 100m
- the powerful vision of the "arch"

experience, frequent exposure to deep diving, and a high degree of training may permit divers to dive on air as deep as 60 meters ...