The antics of dolphins off the beach at Thorne Bay put smiles on faces but when a couple of swimmers ducked below the surface a big surprise awaited.

James Hoseason and his daughter Emma, 9, believe they swam out to the pod just after a calf was born.

"When we got out there you could see ... two very small dolphins and one that must have been born within minutes because it was tiny and it was wedged up, being held between three of them swimming in formation, like protecting it.

"They seemed totally and utterly unperturbed by any humans ... they were showing off with tail-slaps, tail-stands, splashing, all sorts."