They donned their 'yellows' to run down the beach at Hunstanton cheered on by crowds of well-wishers, before plunging into the icy waters of The Wash.
Swimmers had to wade out to a Hunstanton Round Table banner some 50m offshore to claim their certificate.
Santas, grinches, super heroes and pirates all took to the water before the crew launched their bid for the banner.
Lifeboat operations manager Mike Gould said: 'The Hunstanton crew assembled this morning for their annual wash, in a nod to our history we dressed for all weathers.
'Thanks to everyone for coming out and supporting the Hunstanton Round Table and offering us so much warmth and encouragement this morning.'
Warmth was in shorter supply out on the water. For while a mild day had been forecast, someone had forgotten to tell the sea.
'I'm so cold I can't even feel my legs any more,' shivered crew member Louise Kyle after she made it back to the beach and lobbed a couple of extra layers on to get some circulation back.
But once Lou and the crew had dried out and set course for home and their Christmas dinner, they knew the swim might not end up being the only time they'd have to put to sea over the festive season.
For like more than 200 RNLI lifeboat stations around the coast of the UK and Ireland, Hunstanton's volunteers are on call 24/7, 365 days a year.
On average, the charity's lifeboats launch more than 100 times during the Christmas period every year.
Whatever winter throws at them, their crews are ready to battle the weather to save lives at sea.
Their vital work is only made possible by the RNLI’s generous supporters, who help fund the essential kit, training and equipment needed to keep crews prepared and protected.
The RNLI has launched a Christmas Appeal to help crews like Hunstanton continue saving lives.
To donate, visit RNLI.org/WinterAppeal.
Notes to editors
Hunstanton is one of the busiest lifeboat stations in Norfolk.
Its volunteers operate both the fast inshore lifeboat Spirit of West Norfolk and the search and rescue hovercraft
Hunstanton Flyer.
RNLI media contacts
For more information call Chris Bishop, Hunstanton RNLI volunteer Deputy Lifeboat Press Officer on 07584 147219 or Clare Hopps, Regional Media Officer on 09876 234561 or contact the RNLI Press Office on 01202 336789.
RNLI/Chris Bishop
The Hunstanton crew after taking part in the Christmas swim
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 146,000 lives.