ginti
Contributor
I was just using the standards set by the major recreational training agencies like PADI. So, 130ft max depth, clear path to the surface, no mandatory decompression. It's hardly an airtight definition, and I'm not defending it as such. It's just for discussions like this one, you need some sort of frame of reference, and following guidelines that literally millions of divers have been trained by (for better or worse) is a logical place to start. This is especially true in this thread because the OP made no mention of technical diving; actually his question was a little vague and arbitrary, and I probably should have just stayed out of it.
There are certainly lots of 'gray area' dives where one person might think "this is a technical dive, I should only do it with the right tech diving training, equipment, and gasses" while another person would gladly do the dive with only recreational gear and training, on air. Who is right? That's where the opinions start!
I totally agree with you, and I bet almost everyone is. But I believe this point is fundamental to discuss maximum depth, especially our personal limits.
The reason why I believe so is that, as far as I understand, stress can be a significant factor for oxygen toxicity, narcosis and so on. Even if at 130ft oxygen toxicity doesn't play a big role, other effects can (1) become important and (2) be emphasized by environmental conditions. Frankly speaking, considering recreational dives the ones that require nothing more than basic equipment (BCD, tank, regulators, wetsuit, fins, mask, weights and computer), then I can without any problems agree that diving air to 130ft is ok. I do not like it, but I am not going to say it is deadly dangerous, because it is not.
But anything more than basic equipment, even just a light, and the situation changes. In this case, the recreational limit becomes personal. If you are used to perform wreck penetrations at 80mt/260ft depth in the arctic water, sure that any non-overhead diving at 130ft is recreational. But if you are used to dive just to see a bunch of fishes underwater in the tropical sea, like most divers... well the situation is completely different, and even the needs of a light can add significant problems.
In my perspective, basically the maximum depth depends on the diver and on the dive - not on PPO2. However, conservative limits take everything into account and do not ruin too much diving, which is the reason why I like to be conservative.
Going back to the topic, my limit for air diving is 40m in open water with acceptable visibility, shallower (max 30) if visibility is very poor. Actually, I try to follow GUE standards as much as I can (nitrox, 30m max), since I agree with them... unfortunately, it is hard to avoid air where I live, and to find people who want to stay shallow...