was in Carrollton Texas, in my back yard. Our above ground pool, 3 1/2' deep in March. Water temp was about 55 degrees. I was wearing 2 pairs of sweats, my friend Marc, that got me hooked, was wearing his wet suit, 7mm.
After 45-50 minutes, Marc, his wife Terry, and my wife came to drag me out of the pool. No, I was not frozen nor did I look like a Smurf. I was having a blast with Marc's gear.
I have been diving in lakes where the temp goes from 80 to 65 at 30-35 feet. Not wearing a hood gives you a real idea of what a migraine headache feels like.
I dive wet down to the upper 30's wearing a 7mm full with a 7mm hooded vest, 5mm gloves or mittens, 7mm boots.
I have used a dry suit, water skiing variant, which is quite interesting. I will dive dry again, but with a scuba dry suit.
I have no problem getting to the bottom rather quickly IF properly protected.
As to air management, take a class, take to some experienced divers, etc. That is one skill you MUST get a handle on. Not only are you jeopardizing yourself, but your buddy also.
Breath deep and slow on the way down, deep and faster, not FAST, but faster, on the way up. Breathing slower on the way down conserves air for your bottom time. Increasing your rate of breathing on the return trip, speed the amount of oxygen to help outgassing of nitrogen.
Don't be overly fascinated with being able to write some number on the depth line of your log book.
Do be overly fascinated with being able to write the dive number in your log book.