bubble blower:
I was wondering what makes these caverns okay for open water divers but other caverns in the area require cavern cert?
I don't disagree with any of the above comments. However, your question has not really been answered.
The caverns you list all share the obvious overhead hazard of "no direct ascent to the surface in an emergency". What makes them safER than others (though not completely safe) is that they also share the following:
*Obvious way in and back out, difficult to get lost.
*Fairly shallow, limited penetration distance, and daylight reaches nearly all the cavern area.
*Excellent visibility, and enough flow that a "silt-out" is extremely unlikely.
*Wide open space, no real restriction to make it difficult for 2 divers to go through together comfortably.
Cavern diving poses some REAL hazards and can be deadly--so these "easy" ones can give some a false sense of accomplishment . . . on the positive side, they can also expose divers to the beauty of caverns and inspire them to seek the training to do such dives with a high degree of safety.
Remember, even in the "easy" caverns, you must be confident that:
*You can comfortably solve any problems you may encounter while remaining underwater.
*You will not panic when you realize that there are tons of rock between you and breathable air.
*Your buddy is OK with the 2 above statements as well, and can be trusted to stay calm and composed while sharing air and/or aiding you in solving other possible problems.
Dive safe and have fun,
theskull