Irwin is a member of the Sandycove Island Swim Club.
He is the second to have completed a Catalina Channel crossing (after Stephen Redmond) in a time of 9 hours 39 minutes. He completed the Manhattan Island Marathon Swim in 2011, the Lake Zurich Marathon Swim in 2009 in 9 hours 25 minutes, and the English Channel under the auspices of CS&PF in 2008 in 13 hours 48 minutes.
- Manhattan Island Marathon Swim bio
- Catalina Channel Swimming Federation
- Triple Crown of Open Water Swimming
- Channel Swimming & Piloting Federation
- Open Water Swimming
- A Celebration Of Catalina Channel Champions
- Crowned In Cork, Good Things Come In Threes
- Fearsome, Ferocious, Fickle Farallones Awaits The Irish