Okay, my 2 pennies and a personal story now: :doctor:
If you can manage 200M without gear or 300M with mask fins, and snorkel, as well as tread water and/or float for 10 minutes, you're in there, at least with PADI. If you have any doubts that you can do it, find the nearest pool and go there regularly until you're comfortable with those limits. Go get a snorkeling set (or if you're positive you're going to go forward with certification, go ahead and get the scuba fins and mask: you can snorkel just as well with them) and just give the 300M a try; you might surprise yourself. Someone mentioned practice with a snorkel being helpful for the class, and I wholeheartedly agree!
The shorter version is that it's more important to be comfortable in the water than it is to be an olympian athlete. Now for the story:
Up until this year, I had thought about SCUBA certification off and on, but always balked at the though of the swim test. Bear in mind, most of the people I was talking to at the time were Air Force Pararescuemen (PJs), who endure some of the harshest water training in the Armed Forces (close second only to Navy SEALs); their standards and training methods are somewhat, er, more
stringent than recreational diving. Since childhood, I had never been very comfortable in the water, so I figured that was an insurmountable obstacle.
The tide finally turned after a long conversation with a friend who had just gotten certified and he told me what the requirements for the swim test were, and reassured me that they didn't do things like sneak up behind you , yank off your mask, and toss you into the pool. This is, after all, meant to be fun, not a test of combat skills. :14: So, off to the store for a snorkeling set I went, and I spent time in the pool at my apartment complex literally every day until I had figured out that I wasn't going to panic and drown just by putting my face in the water.
Six months later, I'm PADI OW certified and actually prefer being in the water to being on land; I can't believe I didn't do this sooner. I'm not an olympian swimmer, but I can get to shore if I have to without gear (which I have practiced, just to be sure).
Oh yeah: and all of my "lardass" dive buddies can outswim me.
Cheers!