By Carrie Pretorius

Image by Colin Mostert

It is a great privilege to swim with the biggest whale on earth. Sri Lanka is one of the only places in the world where one can fin alongside a blue whale.

Sri Lanka is a hotspot for a wide range of whale species, particularly the pygmy blue whale, Balaenoptera musculus brevicauda, a sub-species of the blue whale. The blue whale, Balaenoptera musculus, is the largest animal on earth, with the largest recorded specimen a gargantuan 30.5m. Biologists speculate that their ability to evolve to such a large size is due to a lack of natural predators. These species are native to the area due to an abundance of food that can be found year-round. This is due to a geological feature 20km offshore: a steep drop in the ocean floor that has resulted in zooplankton rising towards the surface in an oceanic process known as upwelling. The blue whales feed on this zooplankton at a depth of 200m, where they can stay for 10-15 minutes, before returning to the surface for air. Blue whales have small lungs relative to their body size, which is an adaptation for deep diving. Their lungs’ ability to absorb oxygen and rapidly diffuse it throughout their body is what makes them such successful divers.


We slowly rose out of bed and put on our swim suits; it was an hour before the morning sun would wake the sleepy town of Mirissa. The excitement started creeping in: We had no idea what the day had in store for us, except that we would be snorkelling with the biggest animals on the planet.

The tuk tuk picked us up at 6:30am in front of our hotel and meandered its way through the streets towards our boat. On arrival, we were greeted by a few friendly locals. An unspoken sense of excitement and wonder was written on everyone’s faces.

We headed out to sea as the morning sun began to rise in the east, lighting our way on the calm ocean. We donned our fins and got our cameras ready because we knew that luck could strike at any moment. It was not long before the first spray of water was spotted in the distance and the chase began. We only had a few minutes before the blue whale took a few breaths and disappeared into the depths to feed.

The only way to spot these animals in the vast, open ocean is to look for the spray of water that bursts into the air when the whale exhales at the surface. All baleen whale species have a divided blowhole and the air comes out with such force that it forms a water cloud above its head.

There was one particular whale in the area that had been struck by a ship and suffered an injury to his blowhole. He was difficult to spot because there was no spray visible when he surfaced. Instead, we had to look out for his tail and guess where he would surface 10 minutes later.

To be in the water with a blue whale is truly a humbling experience. Imagine swimming in the vast, open ocean in an unfamiliar environment, and then coming across one of its biggest inhabitants. An interaction lasts only about 15 seconds, but during that time it is immediately apparent that the individual whales all have unique traits.

Our most memorable experience was with the oldest and largest whale, characterised by a white spot on the tip of his nose. He was not at all bothered by our presence and slowly swam past us in all his majesty. We nicknamed him “Toppie” and we managed to see him again on another day.

Another whale was characterised by a big, white scar close to his pectoral fin. The scar was more than likely caused by a ship strike. On a few occasions, as individual whales swam past, they would tilt their whole bodies at an angle, in order to get a better look at us with one eye. On occasion, there would be a big thrust of the tail, which reached a height of 10m, and the whale would be gone within a few seconds. Sometimes, however, it was possible to spend a few minutes swimming behind a whale, feeling as though we were almost catching up with it.

A day of snorkelling with the whales usually ended around noon. By this time we were spent from clambering in and out of the boat, all while trying to get the best underwater whale encounters possible. When we returned to shore, we were welcomed by some locals who assisted in bringing the boat on to shore. The skipper had superior boating skills and not only managed to navigate us to the best possible locations for interactions with whales, but also had the ability to beach the boat safely on a rocky shore.

The afternoons were spent going through our videos and photographs and looking for the best shot of the day, whilst sipping a cocktail on the beach. The mornings seemed so surreal and chatting about our encounters helped us relive the truly magical experiences all over again. Just when we thought it could not get better, we were in for another surprise. Blue whale sounds cannot be heard underwater, but we realised that a GoPro could pick up the sounds after we played the video back on a computer. Their sounds are quite distinctive and varied; they could be equated to the sound of winding up a toy car. On one occasion, one of the whales sounded like a small primate calling in the jungle.


The previous year, we had also gone to Sri Lanka looking for blue whales, and we were privileged enough to spend the morning swimming with a pod of female sperm whales. The first sensation I had when one swam past me was anxiety, because of their large size and gaping mouth that proudly displays big teeth.

During our next visit the following year, we were searching for the blue whales when someone on the boat noticed a rectangular, bulbous head protruding from the surface of the water. A single spray, blown slightly to the left, was immediately identified as belonging to a sperm whale. We felt so lucky; we had come across a bull sperm whale which was swimming with a definite purpose. This beauty was double the size of the females we had seen the year before; roughly 17m long.

Sperm whales have the most unusually shaped mouths and heads; one is instantly in awe. Their head contains a waxy cuticle called spermaceti which helps them dive to great depths. This is handy as sperm whales feed mainly on giant squid, which are found at depths of 2 000m. Similar to the blue whale, they have small lungs in comparison to their body size and a flexible rib cage to withstand the big changes in pressure as they ascend and descend. Bradycardia is a term used for an abnormally slow heart rate; this is an adaptation that diving vertebrates have evolved to ensure sufficient oxygen supply to the vital organs of the body. Sperm whales can stay underwater for two hours at a time and this is an example of the physiological adaptations that they have developed to ensure their survival.

Another species of whale we were hoping to see was the Omura’s whale, Balaenoptera omurai, which had recently been sighted off the coast of Sri Lanka. Commonly called the dwarf fin whale, this is an incredibly rare species to see while diving as they are very elusive. We did not manage to see any but a pod of fast-swimming false killer whales was seen a small distance away. In 2012, orcas were seen predating on a sperm whale, but we did not manage to see any on our trip, despite the numerous sightings in the area.

Aside from the abundant whale species, Sri Lanka is also home to five of the seven turtle species. There is a turtle sanctuary close to shore where one can snorkel with green turtles. The visibility is not as good as it is out at sea, but it is still a great encounter with these majestic reptiles. If one is interested in photography, it is possible to get excellent shots as the turtles feed on the algae growing on the hard coral 3m below the surface.


There are many risks that these marine animals face on a daily basis. One of the busiest shipping lanes in the world passes the southern coast of Sri Lanka, where the whales are constantly at risk of being struck. There are currently three lanes that pass by Sri Lanka very closely and these large animals have to navigate through busy ship traffic in order to reach their food source.

Plastic pollution is also putting the whales’ lives at risk. During our trip, microplastics were evident in the pelagic zone as the current pushed them along. This is one of the most harmful forms of pollution in our oceans because it can be ingested by organisms at the bottom of the food chain, such as krill, which then makes its way up to the organisms at the top of the food chain, such as the blue whale. Witnessing this kind of pollution has made me fully realise that our planet is in desperate need of more alternatives to plastic and better plastic-disposal solutions.