The large mammal was playing about the water's edge and chasing a beach ball pushed towards it by a man on the beach on New Year's Day.
Ms Richards soon knew she was watching something special.
''It was playing, just like a big dog.''
At times, however, she was a little anxious.
The man, who had also been taking photos, had been running backwards as the sea lion lurched towards him during the game.
After several minutes the spell was broken and the sea lion lost interest.
The display reminded Ms Richards of captive marine mammals performing at a marine zoo, but she was pleased that when the show was over, the sea lion remained wild and free. And that the man on the beach, and his companions, had been respectful throughout and had generally kept their distance.
Department of Conservation Coastal Otago conservation services manager David Agnew said he appreciated the beach ball incident had been well intentioned, but playing with marine mammals in this way was ill-advised and could encourage other people to disturb sea creatures inappropriately.
Marine mammals, including sea lions and seals, were fully protected by law, and deliberately disturbing them or interfering with them in any way was not allowed, Mr Agnew said.
Sea lions were being seen more often on the Otago coast near Dunedin over the past 20 years and it was important to give them their space, he said.
