Carl Buckley, 28, was enjoying the Christmas break with his brother Adam, 25, when he suffered a sudden cardiac arrest.
Adam called for an ambulance but, despite efforts to resuscitate Carl, he died en route to hospital.
The father-of-one died on December 30 last year and the subsequent inquest revealed that his death was because of heart failure due to underlying heart disease that Carl was unaware of.
Now his cousin, Louise Barlow, 36, from Fareham, is looking to raise awareness for charity CRY (Cardiac Risk in the Young)which conducts research in order to help prevent young sudden cardiac arrests.
Louise has managed to raise £1,787 for the charity through a fundraising page.
She said: ‘It was a big shock to the whole family. Carl was a fit, young, healthy man. We never would have suspected that this would have happened.’
Carl lived in Wellingborough, Northamptonshire and leaves behind his partner Amy and his two-year-old son, Oscar.
Louise added: ‘When I heard that every week in the UK at least 12 young people died of undiagnosed heart conditions, it really shocked me and I thought that it would be a great way to honour his memory by raising funds for a charity that can really help.
‘It’s been devastating for the family and we’ve got in touch with CRY as it provides counselling and support to those who have had to deal with something like this.
‘I have always been close with Carl and want this to help make a difference.’
The charity also supports people who have been diagnosed with potentially life-threatening cardiac conditions and offers bereavement support to families affected by the condition.
It also funds fast-track referral, screening and cardiac pathology services at hospitals around the country.