100 feet below

[S. starfish]

Staying warm is good advice! It can get pretty cold down there and it's a lot tougher to think, even at 30ft, when you're frozen solid.

There's really nothing special that happens once you pass the 100' mark, it's really just a psychological barrier. I don't know where you're diving but it's probably a good idea to bring a decent light, if things get dark-ish you'll feel better having it. As everybody else said, I'd keep an eye on your spg, you go through air faster than you'd think and you will need to ascend with more than 500psi in your tank, how much really depends on how good your air consumption is. Since you're doing the AOW dives you shouldn't be down there too long at any rate.

 

[TSandM]

I just spent three intense days in a class whose stated purpose was to give us the skills the instructor views as necessary for safe diving in the 80 to 100 foot range. A quick summary:

1) Gas planning. How much do I use? How much WILL I use at that depth? How much time does that give me? How much do I need to get me AND my buddy to the surface in an emergency -- safely?

2) Emergency procedures. Can I execute an air-sharing ascent, hold necessary stops, and arrive at the surface in good order? Can my buddy and I execute a mask-off ascent with similar competence? Can we send a surface marker buoy up from midwater, if we have to do an emergency ascent somewhere other than where an ascent was originally planned? Can we hold buoyancy while doing all that?

It's real easy to go deep. I went to 130 feet on my 10th dive. It was in Maui, with warm, clear water, and I was following a divemaster. The issues I listed above had never occurred to me. The dive went fine, and nothing bad happened. But if it had, it most likely would have ended up an accident, because I had no skills to cope at that point.

Your reluctance is reasonable. Think about the issues people have raised, and spend some time shallow making sure you have the skills and understanding to execute a deeper dive safely, even if Murphy joins you.