I did my first open water swim when I was seven.

I'm originally from Dundee and there is a race from the railway bridge to the road bridge with the tide. I nipped my dad's head to let me do it, then spent most of it on his back because it was so cold. I was the youngest person to take part that day.

I swam the English Channel on my first attempt when I was 20. Ten years later I swam the North Channel between Ireland and Scotland. I first attempted that one when I was 18 but failed. That is classed as one of the toughest swims in the world: I was the 13th person to ever successfully swim it and only the third woman. The water is only 12-13C and there are jellyfish, including lion's mane and Portuguese man o' war.

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I'm lucky to have a high pain threshold. I finished the North Channel in the dark having swam through a shoal of jellyfish and been stung across my face. It was nipping at first but it's not really sore until you start to warm up afterwards. That's when you feel them. Sometimes you have welts from the stings, other times it's almost like slime coming out of your skin the next day.

I wear a normal swimming costume, cap and goggles. You get used to the cold. I'm based in Aberfeldy and train in Loch Tay where it doesn't ever get above 12C. For long sea swims we use "channel grease" - Lanolin and Vaseline mixed together - which helps stop friction burns from your swimsuit.

Tackling the Pentland Firth, the logistics was the trickiest part. There had been attempts before from St Mary's Hope to the tip of Scotland, but I went from Hoy to the beaches in front of Castle May which is nine-and-a-half miles. Other swimmers had taken a shorter route but we looked at what was most likely to be finishable. Local fisherman Robert Smith agreed to be my boat captain. He knew that stretch of water well so all I had to concentrate on was my swimming.

It took me four hours and 41 minutes to complete the Pentland Firth. By comparison the English Channel was 13 hours and 55 minutes, while the North Channel was 15 hours and 26 minutes - the longest I've ever been in the water.

There can be debris but you just have to swim through it. Sometimes you can taste oil in the water or there is garden waste that has been dumped in rivers. I swam around Manhattan Island during a thunder and lightning storm. There were wooden sleepers going past that had come out of the storm drains and all kinds of rubbish. Let's just say you wouldn't want to look too closely.

After Manhattan Island I wasn't well for a couple of months but it's part of the sport. There is an old belief among open water swimmers that if you drink full fat Coca-Cola afterwards, it supposedly kills all the bugs in your stomach.

I'm attempting the Catalina Channel in California in October. That one is 20 miles and best described as America's version of the English Channel. Before then I'm hoping to be the first person to make a solo, non-aided attempt on The Minch. A group of guys did it two years ago in wetsuits but for my sport the rules state it must be non-aided which means no wetsuit.

The 2014 WOWSA Global Open Water Swimming Conference will take place at Mount Stuart on the Isle of Bute from September 20-21. Visit vigourevents.com