More than 120 took part in the Sunny Hunny Triathlon.
After a 200m swim in the pool at the Alive Oasis leisure centre on Hunstanton seafront, they took to their bikes for an 18km ride around the town, before finishing off with a run along the Prom and cliff tops.
Race director Chris Playford, from organisers King's Lynn Triathlon Club, was pleased with the turn-out.
'It's really good, we've got 120 - 125 taking part,' he said. Asked why the club had opted to raise funds for the Hunstanton RNLI for the second year running, he added: 'They're local and any of us might need help from them one day - we're all locals.'
Jon Butler is a hovercraft pilot and inshore lifeboat crew member with Hunstanton RNLI, whose life saving work would not be possible without kind donations from its supporters.
'It was a killer,' he said after crossing the finishing line. 'The north wind didn't help, but the boys helped me on the run.'
Jon's sons Rowan, aged eight and Eden, five, made light work of the final stage with their dad - which included the dreaded zig-zag climb on a walkway from the Prom to the cliff tops.
Niamh Walter, whose partner Ryan Darby is a helm on board Hunstanton lifeboat Spirit of West Norfolk, was one of the next home.
'The helm said he'll be doing it next year,' she said after crossing the finishing line on The Green.
Last year's Sunny Hunny Triathlon raised £750 for the RNLI. Proceeds from this year's swim, ride and run are still being counted.
Notes to editor
Hunstanton RNLI operates both an Atlantic 85 fast inshore lifeboat, Spirit of West Norfolk and the search and rescue hovercraft
Hunstanton Flyer from its station on Sea Lane.
Like more than 230 stations around the coast of the UK and Ireland, the lifesaving work of its volunteers would not be possible without the kindness of the RNLI's supporters.
RNLI media contacts
For more information call Chris Bishop, Hunstanton RNLI volunteer Deputy Lifeboat Press Officer on 07584 147219, or the RNLI Press Office on 01202 336789.
RNLI/Chris Bishop
Niamh Walter crossing the finishing line in the Sunny Hunny Triathlon
The RNLI charity saves lives at sea. Its volunteers provide a 24-hour search and rescue service around the United Kingdom and Republic of Ireland coasts. The RNLI operates 238 lifeboat stations in the UK and Ireland and more than 240 lifeguard units on beaches around the UK and Channel Islands. The RNLI is independent of Coastguard and government and depends on voluntary donations and legacies to maintain its rescue service. Since the RNLI was founded in 1824, its lifeboat crews and lifeguards have saved over 142,700 lives.
