OMG 45 degrees. I'd want a heated dry suit or a heated submarine for that
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As a newish diver who likes his own stuff I would suggest buy everything but buy entry level or 2nd hand. Best part about diving is you meet lots of new people who have lots of different ideas so use their ideas. BTW I have bought everything I need. Is it exactly what I want no. I even bought tanks but only payed $180 for 2 faber 85cfm. Are they what I want? no they are too big but I will use them and they do the job for now. Not going to enjoy them when I go side mount.
I did my OW and bought my BCD first and sort of regret it. It doesn't suite what I want to do now but it does suite carrying stuff I don't want in my hands and dangley things annoy me as it is a fumble. Also there are so many variables to diving which even affect what type of fins are going to be best. Also are you going to be able to dive near where you live or only when you are on holidays as generally home is cold, holidays is warm so different wetsuites, boots, gloves.
Things which wont change well most circumstances are mask, computer, weights (buy small ones), small torch for nooks and crannies (ebay $10) and that's about it.
You do know you will want the minimum backups of spg, torch, air. Also if it isn't on your wrist it is a hassle. I love my computer. Uwatec Smart Z 2nd hand. Doesn't have a compass which I use quite a bit. I used to follow now I lead a lot. Should have bought a wrist mounted compass. I also reckon those consoles with everything on them are crap. Used them initially and hated them. Always having to fumble about and look. Now I just glance at my wrist and go air good, rbt good, that's all I really care about, oops missed something important, fumble for my compass, direction good.
Yep you are in for some spending so seriously don't buy what you "think" you need initially as you will be wrong.