Ian Bradbury was out on his jet ski on Saturday just south of Kaikōura when he was surrounded by dolphins - "hundreds of them".
"I've never seen so many," Mr Bradbury said, as the dolphins took turns bow-riding his jet ski.
He was used to them doing this and said they seemed to like jet skis "because they know they're not going to get hurt".
Mr Bradbury also said the dolphins were probably particularly interested in him "because of loneliness, there's no tourists around".
He was out on his jet ski looking at the huge slips caused by the magnitude 7.8 quake when he came across the dolphins, and took footage on his iPhone, which luckily didn't fall in.