Roger Munns was in Toku - a region of sheltered bays and inlets on the isolated Pacific Ocean island - in the hope of catching on film the mating rituals of giant humpback whales.
But while he was able to observe plenty of bulls competing with each other to win a mate, the star of Roger's production turned out not to be one of the fully-grown, 45ft gentle giants.
Flipper to flipper: Underwater cameraman Roger Munns gets up close and personal with the calf
For while the heavyweight males were obviously too pre-occupied with their own love match, an inquisitive calf approached the cameraman looking for a playmate - and spent the next hour posing before the lens.
Roger, from Cornwall, said: 'I've heard about calves doing this but I was not prepared for the playful nature at all.
Getting the hump: The whale cavorted before the camera and appeared inquisitive about his new playmate
That's no bull: While the adult males fought for mating rights, the young calf was much more interested in playing
'Up close you suddenly realised just how big it actually was. The games continued for an hour and I have to admit it was probably one of the most enjoyable hours I have spent in the water.'
Let's roll: The baby humpback enjoyed playing a game of tag
Role reversal: Normally behind the viewfinder, wildlife photographer Roger poses for the camera while exploring the waters around Tonga