Free divers are people who dive very deep with no air tanks. They can hold their breath for stupidly long periods of time, like over 10 minutes - good luck trying to drown a freediver in the bath (if you are that way inclined)
Try a tandem sky dive Deb, it's one of the best things I ever did, falling over a mile at 120mph or so with loads of noise and then once the chute opens, its absolute peace and quiet and a fantastic view of the ground, you're about a mile up when the chute is deployed, so you get a great view.
50-55 with the odd 60 sounds fine, but check the GP if worried - does yours use askmygp?
I used to work with a girl who was a qualified skydiver she was always trying to get me to have a go but I really can't do heights.
I was on an outdoor pursuits weekend down on Dartmoor years ago and our instructor organised for us to do the high ropes course.
I was fine setting off but then had to be rescued half way round as I just freaked out on one section that clearly wasn't designed for someone less than 5ft tall. Standing on a thin wire then having to lean forward to grab another wire that meant I was looking at the floor having to shimmy to the next section.
It took nearly half an hour to calm me down enough to climb down the escape ladder.
I then went with a few girls from work to the go ape one at the Trafford centre which was like a kids playground in comparison. I got the harness on and joined the qué then freaked out again just before we went through the gate. Just the thought of it was enough to get me hyperventilating and needing first aid.
No I don't think mine does have that option mate.