Scuba diving has approximately the same accident/death rate
as bowling.
An individual cannot just walk up to a dive operator
and rent equiptment and go dive without showing
proof of certification (and oftimes a log book to
back up the c-card).
There is no certification required to ride a bike,
no educational requirements or governing education
agency.
Anyone can purchase
scuba equiptment but it takes a c-card to
get the tanks filled (no air, no dive).
Anyone can purchase a bike and go ride.
Different levels and types of diving require
specialized education (i.e. cave diving, wreck diving),
and without it no reputable dive operator is going to
take a diver into those environments without proof
of specialized education.
Cycling? Neighborhood streets or highways
they are all fair game.
Hazards of diving may be static in that they
are a known quantity. but the occurance isn't.
i.e. a diver can do everything right (depth, length
of the dive, ascent rate, safety stops) and still
can get the bends (decompression sickness).
I'm a certified scuba instructor (PADI) and safety
is of utmost importance, from the first discover
scuba class up to course director (the guys who
teach instructors)class, cycling has nothing remotely
like that.

marty