That's according to underwater photographer Tony Wu, who visits the island regularly to document the way humpback whales use the area to breed.
He says he managed to count 48 whale calves born in Port of Refuge harbour this last season, which is a lot.
But Mr Wu says the Tongan whale watching industry needs to make sure not to promise tourists that the whales will come close to them or touch them.
Presenter: Bruce Hill
Speaker: Underwater photographer Tony Wu
WU: I don't know if anybody really knows anything about the birth rates in Vava'u or of these whales in particular. I mean there are certainly studies that have been done by the scientists in the southern hemisphere, but just from looking at the numbers of females with babies that I've seen over the past four or five years, this year was definitely a bumper crop, at least in the number that stuck around. To give you an idea we had about twice as many 2010, and about one and a half times as 2009. Going back from memory we're probably at around that same ratio for all the years before that, one-and-a-half to two times.
HILL: Vava'u is one of the few places in the world where there's actual whale watching operations in which you can actually swim in the sea next to the whales. I've actually done it myself and a whale and calf came over and had a look at us, it was quite a remarkable experience. But is that kind of whale watching operation, that kind of interaction with the whales, is that good for them or could it potentially harm them?
WU: I've been going to Vava'u, well the first time I went was 1998, and I've been going every year since 2003, and I spent more time in the water with these whales than any other person ever has. One thing I can tell you about the whales is that they are complicated animals, they are complex. There's no if a then b. They have unique dispositions, they have personalities, they have moods, they have social interactions. So I think when you consider a question like this, you have to take it in the context that they are wild animals, they do what they're going to do, and if you respect that and you let those animals dictate the course of any interaction, it's a great experience. As you had in your experience there are any number of times when the animals pro-actively seek out attention, they come over, they look at you, this is adults, this is babies, they may play around you. But the key is that they decide. There's a lot of times if you go over there and you see lots of whales, but none of them have any interest whatsoever in people. In those circumstances you have to respect them, give them their time and their distance and let them do what they're doing. So on the whole I think as long as the whale watching industry handles the animals this way, which they do, then it's perfectly fine for the animals.
HILL: Do some people go to Vava'u to swim with the whales with perhaps a false or inflated expectation about what would happen? I mean sometimes people get this idea they're going to spiritually commune with the whales, and they sort of build up perhaps false hopes?
WU: Yeah I think some people do, I mean it's not a lot of people, and certainly being in the water with such a large animal, huge animal, I mean 13, 14, 15 metres is a spiritual experience. It can be easily a spiritual experience. But I think going over there with the expectation that you might have some sort of magical experience like with some sort of quasi religious type of experience is not a good thing. I haven't come across a lot of people like that, but people who do go over there with those types of expectations could be disappointed. I mean these are animals, they do what they do and they're not really that concerned necessarily with people, except those times when they are in a playful mood. I think the whale watch operators there do a very good job of explaining the situation to their guests, telling them that the animals could be interested, they could not be interested, the conditions, the water conditions, the wind conditions could allow for people to get in or maybe not, and set up the right sort of framework and set of expectations for anybody who goes over there to manage what you think when you go over there. And I think if somebody is contemplating going over to Tonga it's very important to have a realistic set of expectations. To go over there knowing that well if you spend a week over there hopefully you will have a wonderful experience and you'll have whales that come over and are very curious and interact with you and look you straight in the eye, it's great. But given it's nature and these animals are there to meet, mate, to breed, to do whatever they're doing, they have important things to do and you could very well end up after week not really having had that experience.