Humpback Whales on Tonga

Humpback Whales seasonally visit Tonga to breed. David Donnelly and Wildiaries promote ethical whale swims. These eight-day trips are designed to provide visitors with maximum opportunity to not just encounter whales but build a true connection with and understanding of Humpbacks, plus immerse themselves in the customs of Tonga.

Wildiaries’ founder Simon Mustoe joined Blue Water Explorer this September. What follows is a day by day account of the five days spent on the water with fellow whale enthusiast and expert whale swim guide, David Donnelly. 

  • All other day swim operators target cow-calf pairs, which is something we won’t do for the sake of a swim (see our article here). Instead, we offer a more interactive experience. 
  • Having a few days means the team can spend a lot more time seeking whales that are receptive to swims. The trade off is that the overall duration and diversity of encounters is richer.   


This was my first visit to Tonga and I was there purposefully to understand more about the whale swims run by Dave. 

For many years I’ve studied marine mammals. I’ve spent weeks surveying and recording behaviour on board ships as well as running whale watching trips from time to time off the east coast of Australia. 

I wasn’t prepared for the sheer diversity of encounters in Tonga. The range of behaviours and type of behaviour was astounding. Humpback Whales were doing things I’d never encountered before, everything from choruses of dozens of singing whales to competitive pods literally striking each other with tails, bubble blowing, interactions with dolphins, travelling groups of 10 whales together ... five days was long enough to see so many behaviours and even experience heart-stopping encounters with inquisitive whales deliberately coming to within a few feet of us swimmers.  

Throughout the trip we came across cow-calf pairs. We’d slow down and pass them quietly, stopping long enough to record the data for scientific purposes. Many of these animals were resting silently at the surface.

Day 1 - Competitive pods. 

The first day we headed out north and after two or three hours of searching came across a group of five whales including a cow and calf, being actively pursued by three subadults who were displaying considerable aggression to each other.

They would lunge head first, arching their back inwards, before punching the whale below with their tail. Merely watching this unfold above the surface was remarkable. I’d never seem these types of encounters before. We cruised parallel to the pod at a distance, matching their speed at between 12-15 knots - a speed the whales kept up for an hour or so, before the escorts split off - which was the moment we were looking for.

Swimmers prepared, we slipped into the water ahead and to the side of the group and before we knew it, they passed by in formation. That was the first encounter of the trip and topped off a remarkable day, which included a visit to Mananoa Island, a paradise-like lagoon fringed with beautiful coral reef and where a single 4-foot Leopard Shark (harmless and beautifully-marked) was resting on the sand floor.

The Tongan boys caught a Giant Trevally on the journey home that was served that evening for dinner - one of a number of fish that can be sustainably and locally caught, which is a far superior option for meals, than eating importedfish from industrial fisheries.

Day 2 - playful whales

The morning search for receptive whales was difficult and we were about to give up and head to the island for a swim when Blue Water Explorer’s partner vessel called up to say they had two subadult whales that had been approaching the boat for some time.

On arrival we deployed swimmers and the two whales came straight over. inquisitive would be an understatement. Within minutes, the pair were rounding the swimmers, surfacing directly below, spy-hopping within a metre or two of swimmers (all in clear water).

We took a break from the swim for a short while as three other whales appeared. The mood changed and the animals started fast swimming and vocalising. Aggression ensued and we retreated to the vessel until the moment passed.

Safety in the water is paramount and the Tongan guides’ experience includes diver safety training, first aid and thousands of hours in-water. At no point was anyone in danger but it’s satisfying to know that precaution applies long before there is any risk.

When it comes to proximity of whales, this encounter was to prove the most compelling of the week and Captain Dave was quick to point out that any swim can be your last. It also proved, again, the benefit of seeking out the ‘right‘ whales, as opposed to forcing a swim.   

Day 3 - Short-finned Pilot Whales, Humpbacks, dolphins

The third day on the water was forecast for nearly no wind so we took the chance to head into deeper water.

That day is the subject of another article and video ... read here. The conditions were ideal for swims and for searching the ocean for other marine wildlife. First appearance was a group of oceanic Bottlenose Dolphins that were swimming in convoy with two Humpback Whales, then the appearance of a pod of Short-finned Pilot Whales.

We ended up swimming with the Pilot Whales but at least twice during the encounter Humpbacks appeared unexpectedly below. It was interesting to see different species coming together underwater. So often our view of these interactions is in two dimensions and the entirely different perspective this provided was a unique insight to a world we hardly ever get to see.  

Dropping the hydrophone in the water, we could hear countless Humpbacks chorusing throughout the lagoons. 

Day 4 - Rough-toothed Dolphins and Humpbacks

The majority of this day was quite barren, with the exception of the first hour of the day.The very first pod of Humpback Whales encountered were accompanied by a pod of about 15 Rough-toothed Dolphins.

These dolphins are true pelagic species, rarely if ever seen inshore. It’s hard to know whether there was any angst between the species. The Humpbacks were swimming fast, dolphins were riding ahead of the whales’ snouts  but also driving hard against the whales’ flanks, knocking harmless remora (suckerfish) off their sides and eating them.

There was much vocalisation under the water both from the dolphins and the whales. This nature of encounter is so rare, it only lasted a few minutes and we were privileged to witness something few, if any one, has ever observed.

So it didn't matter that it lasted a short time, we just witnessed something truly priceless and any of these moments could be the moments that justified the entire trip!   

Day 5 - Travelling whale groups (10 animals)

On the final day forecast conditions were for strong north-westerly winds which didn’t eventuate. Nonetheless, we headed south east into the lee of the island hoping to find whales but they were few and far between.

For several hours we encountered whales who were not receptive to swims - after a couple of passes, it’s usually clear whether they are going to stick around or not. Pursuing them isn’t just silly but rather a waste of time. If a whale doesn’t want to swim, time is better spent looking elsewhere.

A Yellow-bellied Sea Snake provided a moment of respite during the searches. These live their entire lives at sea and this foot-long individual (a juvenile) was feeding in water 400m deep.

Flocks of seabirds flew overhead including Lesser Frigatebirds, Red-footed Boobies, White Terns and Black Noddies. A single Hammerhead Shark drifted at the surface in current-lines with its characteristically tall dorsal fin emanating above the surface.

Before the day was out, we encountered a competitive pod of 10 whales travelling fast. They showed some curiosity in the boat and on the first swim, several turned back to the swimmers to eyeball them in the water. The visibility wasn’t as good but at one point I could see a tight pod of seven animals swimming along gently about 20m directly below me.

Large groups like this aren’t that common and again, being able to see them underwater, despite the visibility deficit, was quite remarkable. A second pod later contained a cow and calf, similar to the pod we found on day 1, being pursued by an adult and young males.

We dropped the hydrophone in the water and were subjected to ear-piercing screams and whistles from what was probably the dominant animal. The calf was caught among the ruckus and must have been terrified. The stand off between the cow and the other animals lasted about thirty minutes before the cohorts split off. 


Overall it was a fascinating and exhilerating week. For someone who has studied and worked with whales for years, it revealed so much about the nature of the whales that I never knew before. What perhaps struck me most of all, was their nervousness and awareness around people. Apart from the few whales that seem almost too bold for words, most are very tentative and will react to you whenever you're nearby. 

Being in the hands of people who put your safety first and have a profound appreciation for the behaviour of these animals at an individual level was a relief.

The patience and attention to care was what inevitably created the best encounters. Without that, we would not have seen half of what we did and I suspect, that we spent more time with whales that week, than all the other island's boats put together. 


Wildiaries •