Another solution is to get certified on a rebreather. A used Drager Ray (semi-closed) can be had for about $900 US. (Albeit the Ray is an entry-level rebreather, it’s a bargain at that price.) Course is a few hundred more; and you have to take Basic Nitrox as a pre-req. Rebreather diving changes the equation of air consumption completely. Depth hardly matters at all. Your "air consumption" also doesn’t matter much. No dry-mouth. Those are the big pluses. But no free lunch. Lot’s more dive prep. Lot’s more keeping track of things. Lot’s more mistakes to make. If you aren’t meticulous, you should stick to regular "open circuit" scuba. Cost per hour underwater is somewhat higher. Regards, Mark