Soon afterwards the pod appeared in the bay and spent the next three hours frolicking, leaping from the water in pairs and jumping over swimmers' heads.
Mr Western's guests, from Germany, France and the UK, saw the passengers on other boats pile into the water and asked if they could get in too.
It was hard to say who was more entertained by the interaction, the dolphins or the humans.
"The guests have smiles on their faces they still haven't got rid of."
Mr Western - who also happens to be an excellent photographer - is on the water almost daily in summer but said it was the best display he had seen since 2009.
Among his guest was a German photographer who had been working with Northland orca expert Ingrid Visser. Friends reported seeing a similar pod playing with swimmers at Oke Bay, near Rawhiti, a day earlier.
Swimming with dolphins is banned when calves are present but this pod consisted of adults only.