THE poisonous blowfish lurks, unnoticed beneath the ocean before suddenly puffing up to double its size and shooting toxic spines into its unsuspecting prey.

It is one of the most poisonous creatures in the world but for yachts-woman Emma Pontin the blowfish became her weapon against cancer.

In fact the disease and the deadly fish became one and the same, explains freelance skipper Emma, 37, who was diagnosed with breast cancer in 2006.

Finding it impossible to fight invisible cancerous cells, Emma visualised a blowfish attacking her body instead.

"I needed to be able to see this thing and focus on hating it and what it was doing to my body," she explains.

The blowfish - so often encountered by Emma as she navigated the world's oceans - proved to be an image the courageous yachtswoman could detest.

For a woman used to facing the might of the ocean in gruelling transatlantic races, beating the blowfish was just another challenge she was determined to win.

This time instead of storm force gales and life-threatening waves, she faced punishing chemotherapy sessions, radiotherapy and surgery to remove her breasts.

Now Emma - who was competing in transatlantic races within weeks of getting the all clear from cancer - is writing a book about her experience and looking forward to her wedding.

But the future wasn't always so certain.

In 2006 as Emma was in Gibraltar preparing her boat for a transatlantic race from the Canaries to St Lucia, she received a phone call confirming her worst fear - she had breast cancer.

"My first thought was no, I'm too young'," remembers Emma.

"But my aunt and my grandmother both died of breast cancer so I suppose I always assumed it would get me.

"I accepted it but I cried like I had never cried before. Then I went into stunned mode."

Within four days, Emma was back at home in Hamble and admitted to hospital for a left mastectomy.

"It was have the surgery or die," she says matter-of-factly. "But choosing to have my other boob removed later and the reconstructive surgery a few weeks ago was something I struggled with. I thought if it's not broken don't fix it' but in the end I realised I was broken. I was constantly checking my right boob and started to hate it. In the end I just wanted to get rid of it.

"And I wanted to look like other women. I wanted to be a normal girl again.

Emma approached cancer with the same determination she would a yacht race.

"I just thought right, if you don't do something about this you're going to die'. I went into Miss organised, efficient mode."

During her radiotherapy Emma found the strength to run Race for Life with record-breaking yachtswoman and personal friend Dee Caffari, raising more than £800 for Cancer Research UK.

And within three days of starting chemotherapy she was back on the water, her hopes pinned on skippering the following year's transatlantic race from the Canaries.

"Sailing became my drive, my focus. I'm a stubborn individual and now I'm so grateful for that.

"I suppose I saw chemo as an annoyance, but I respected it and knew I had to do it to get better.

"I know I was very lucky because my experience of chemo wasn't as physically challenging as it is for many people. I didn't get sick so I was still able to go out and do my job."

However the mental challenge cancer presented was immense.

"I had 19 months of wobbles - times when tears would just roll down my face. I wasn't looking for attention. I just wanted people to ignore it and then I would be ok.

"Once, it happened when I was on the water because I thought this could be the last time I do this'."

Emma also struggled with her dramatically altered appearance, keeping her head down to avoid seeing her reflection in the mirror.

These are all issues she explores in her book Beating the Blowfish - a "Bridget Jones' style diary" initially written to help friends and family understand what she was going through.

"I want someone to read it and think oh, that's just how I'm feeling' and to see it's okay to have emotions that aren't dictated by the medical profession.

"There's also a lot of humour in there which is important when you're fighting such a conniving, deceitful disease. Hopefully it will reduce some of the fear surrounding cancer."

Emma hopes her diary will also be a comfort to cancer patients' loved ones.

"People forget about the person who's standing beside you in all of this," she says thinking of her fiancé Rich, who not only supported her through her illness but proposed to her too - even though Emma gave him the option to leave her when she received the devastating diagnosis.

"Rich has had to love me through this. He's had to look after me and face the fact that his girlfriend might die. Neither of us knew what was around the corner."

The pair - who met while working on a yacht - are getting married in July followed by a blessing in Rich's native Australia.

"At one point I didn't think I would make my wedding day. We set a date but I refused to talk about it and I wouldn't book anything. Then I got the all clear and I thought I'd better get a wriggle on!

"Cancer does change you but I'm still finding out exactly how. Part of you wants to grab life and do everything but another part thinks you should wrap yourself in cotton wool and do nothing. Like when I was in a race and I just thought what am I doing? I've just fought for my life and now I'm sitting here on a little boat in the middle of a storm'."

But Emma isn't about to stop challenging herself just yet.

Her future plans include circumnavigating the Tropic of Cancer, running the New York Marathon, cycling from Land's End to John O'Groats and, of course, running this year's Race for Life in Winchester on June 11.

"Running Race for Life last year was normal and having cancer wasn't. I had the urge to do normal things. It's such an excellent event and I'm going to do it every year I can.

"Now that I have had first-hand experience of cancer, I want to let others know it can be beaten."