Pateeny, You otta think about a wetsuit. you wont last to long without one. Once you get below the thermocline there will be a 10 - 20 degree differance. cold takes all the fun out of it. A used 5mm wetsuit and a 10 lb (2- 5 lb) weight belt $100. will make all the differance in the world. The only think is once your waring a "closed cell neoprene " wetsuit some laws of boyance will apply and you might need a litte in-water training.
Theres not much sientry to breathhold diving but there are some tricks to extending your time underwater and with that, increases the chance of passing out. Never dive alone.
I've spent 10's of 1000's of hours underwater, working and the novilty findly wore off. my wetsuit has costom pluming for hot water. 4 gallons a minute. I plug in at my chest. 5 small hoses run to my toes and hands. 100 degree water. You should feel what thats like in january. Ha!
You will have much fun for many years and eventually get certified in scuba. Practice good watermanship and be safe!