Her daughters Jessica, Brittany and Monique, and their cousins Danielle and Jordan, began patting Moko and swimming around.
"They were absolutely buzzing."
The excitement of new playmates must have been too much for the young dolphin, who went into a jumping frenzy.
"It got a little bit scary, so we decided to bring the children on the boat."
Mrs Arthur filled her memory card with photographs of the encounter and said getting the perfect shot was a case of being in the right place at the right time.
SECOND PLACE
David Dale took this shot of his wife Nene and daughter Kate, 11, in the throes of an epic mud fight.
Mrs Dale said she and her husband were busy building a retaining wall at their property in Red Beach when the ground became messy with concrete and mud.
"Then Kate decided to throw some mud at me and it was on," she said.
"I had just eaten a mouth full of mud when my husband took the photo."
Mrs Dale admitted that Kate came out on top.
THIRD PLACE
Spencer Tarawa's photograph captured a game of cricket between his father Herewini Tarawa and mokopuna Tane-nui-a-rangi, 7, on January 2.
The extended family were enjoying two weeks at their bach in Whanganui Bay, Taupo, something they do every year.
Herewini Tarawa, 69, uses a walking stick and is not as flexible as he used to be, so he used a chair to help him with his bowling.
Herewini suffered a heart attack the day after the picture was taken.
Spencer Tarawa said his father was recovering well in Waikato Hospital after a triple bypass and would be able to return to his home in Taumarunui next week.