In a case of being young at heart, an elderly man's tomfoolery with his grandchildren has left him seriously hurt at an Auckland beach.

The man in his 80s was attempting to jump off a six-metre cliff while playing with his grandkids at Little Manly Beach in Whangaparaoa on Boxing Day.

However, he slipped and fell on the rocks, suffering multiple injuries, according to Auckland Rescue Helicopter Trust.

The elderly gentleman was pulled from the water by a fire crew and flown to Auckland City Hospital in a serious condition.