Underwater, no one can hear you burbleburbleburble

We've found a really, really good SCUBA club. It's $20 to join for the year, and then $35 per dive including all your gear except flippers and mask. Except it didn't go according to plan

When you are diving you need the following
Flippers
Boots
Wetsuit
Weight and belt
BCD (buoyancy Control Device - the jacket thing that everything connects to)
Tank
Regulator (the tubes and mouthpiece etc.)
Mask
Snorkel (optional)

We all got set up at the dive shop, I remember all of the above list except:
A snorkel: no problem, don't need it
A BCD: awww crap. Can’t dive without a bcd, we're an hour away from the dive shop.
The instructor was so good with her air that when she came back out of the water with the rest of the group I borrowed one of their BCD's and she took me out on my own; it is a really good dive club.
Now the surf was a little high and I must admit to never going scuba'ing from the rocks, I've always got in from a boat. We were also wearing 5mm wetsuits as the water was a bit chilli (22 hahahahaaaaaa) which makes movement slightly more restrictive. Getting in was real nasty as the surf was hell bent on pushing me back in to the rocks then going down was even worse. I had to empty all my air out my bcd, empty my lungs and still push hard to get down. You see while I am a 'qualified' scuba diver, it is also safe to say that on the big list of diver talent I'm firmly between Neutrally buoyant corpse and floating corpse. Visibility was about 4 meters and there was lots of little fish about, even a couple of big (80cm) groupers.
I'm swimming away, The instructor off about 5m in front and I'm enjoying all the little fish, but kind of lamenting there wasn't anything really big to look at. Mind you, I didn't want too big, as there are sharks in the area (though not so likely to be around by the rocks). Swimmy swim I go, round this rock, along that cleft etc. then suddenly I feel that I should look a little bit left (into the ocean) and a little bit up (normally up to the surface but because of my swimming it was sort of diagonal). Cold dread enter my body and there, not 3 feet from me was, and I swear this is the truth, was ooo it must have been nearly 6 feet in length, a giant other scuba diver.
Turns out that this is a popular spot and we weren’t they only group to be diving that day. Course I'm sure the other diver didn't feel that thrilled to be diving with someone else either, especially someone leaving a large brown wake behind him...