Rosie Allan-Jones: Tombstoning: I was careful and sober. And then I jumped...

Tombstoning – jumping off rocks or piers into water – has been getting some enthusiastic press. Last week, in his IoS column, Dom Joly explained how the sport has run in his family for years. How proud he was as he watched his daughter hurl herself off a cliff into the waters of Lake Joe. Tom Whipple from The Times joined a tombstoning website for his first jump and recommended the sport as no more dangerous than paragliding. In the light of Lee Griffin's death last week, these pieces might now be thought a little reckless. I can tell you what can happen to a tombstoner.

A year ago I was on holiday in Dubrovnik, Croatia. There is a point just outside the town where tourists and locals go to frolic by jumping into the sea. My boyfriend and I decided to check it out. We were fairly disappointed; the rocks weren't that high, we weren't scared. After jumping off a few of the lower rocks, we watched amazed as a young boy scaled up some massive boulders to a point about 90 feet up. He jumped, surfaced and proclaimed: "I have been doing that since I was 10." A competitive match had been struck inside us.

We climbed up and I found myself sitting on top of a rock, hugging my knees, shaking and occasionally peeking down to the calm ocean below. Above me a baiting gaggle of French youths encouraged me to offer myself up to the sea. What was the worst that could happen?

I don't remember jumping, just the build-up. I thought of my father, and how proud he would be. I was falling for three seconds. In the water, I couldn't breathe. All I could feel was an intense pain in my back, as if I had been sliced through. My boyfriend jumped in and swam me over to the rocks. I started to black out but managed to tell him that I couldn't hold myself up, that the pressure on the base of my back was too much. My spine was collapsing.

In the hospital a surgeon looked at me with sad eyes and uttered the words I had refused to think of. "You need to be operated on immediately, the position of the bone in your back means that you are in serious risk of brain damage and paralysis. We need your consent." They gave me some forms to sign. They were in Croatian. I signed.

It was never certain that I would come out of the operation able to walk. After hours in surgery to insert the plates and screws that would hold me together, I could wiggle my toes when I came round.

Two weeks later I was flown back to England in an air ambulance. The British surgeon talked me through my MRI scans and X-rays. I had broken my first lumbar vertebra into five pieces, cracked my sternum, damaged three vertebrae in my neck and pulled a ligament in my lower back. I had permanent damage to my spinal cord. He stressed that I had been incredibly lucky. I had survived. This Wednesday I will have a daunting operation to remove the scaffolding supporting my battered spine.

So when people say tombstoning is safe if you're sober and the water is deep enough, hear this. It is the water that can do the damage. "You wouldn't jump 30ft into concrete," Tom Whipple wrote, "So why would you jump 30ft into a foot of water?" In other words, if it's deep, it's safe. What he failed to note is that hitting water at high speed is the same as hitting concrete, regardless of the depth.

I was not drunk, the water was not shallow and there were no rocks. I hit the water at an angle and that was what shattered my spine. All the safety checks in the world count for nothing against this inconvenient truth.