Humpback whales have used the Dominican Republic’s Samaná Bay and Silver Bank coral-reef sanctuary as a nursery and breeding ground for thousands of years. Taino drawings on the limestone caves of Los Haitises depict breaching whales in the Bahía de Samaná and Columbus made note of their presence here in 1493. The whales return each December after nine months of relentless feeding in the North Atlantic; by late January more than four thousand of them, the entire northern Atlantic population, move around the waters of the country’s northeastern coast. They’re at their liveliest in Samaná’s tepid depths, as males track females, compete for attention and engage in courting displays, while mothers teach their calves basic survival skills. Don’t allow yourself to come here during the winter without taking an excursion to see them; the season generally runs from mid-January to mid-March.

Adult humpbacks grow to nearly 15m in length, weighing up to forty metric tonnes and are black with distinctive white patches. Their name comes from the singular arching of their backs when they dive. Their mouths are filled with baleen, hundreds of fibrous sheets that hang from the upper jaw and act as a sieve that traps tiny crustaceans. On their bellies are ventral folds – retractable pleats extending the length of their bodies – which expand, allowing the animals to hold massive amounts of food. Their enormous tails possess unique patterns of white blotches, which marine biologists use to identify individual whales in a similar way to human fingerprints.

Among the behaviours you may see while whale watching are: breaching – hurling the entire body above the surface before landing back down in a spectacular crash; chin breaching – bringing the head above water and slapping the chin against the surface; lobtailing – raising the tail and smacking it against the water; flippering – rolling the body and slapping the flipper against the water; diving – arching the back and then sticking the tail straight up in the air in preparation for a deep descent; and the trumpet blow – a tremendous, low blast that can be heard from several kilometres away.

Humpbacks also engage in the whale songs for which the species is well known – an eerie combination of moans and chirps formed into short phrases that are shuffled and put together in a basic form of communication. Only males sing and they do so far more frequently here than in the North Atlantic – which leads to speculation that songs are used to find a mate. Humpback groups in each region of the North Atlantic develop their own distinctive music, but a single song prevails while around the Dominican Republic. This is constantly evolving, probably due to the breeding success of the males who deviate from the original. Therefore, each winter starts with last year’s song but this is slowly revised over the course of the ensuing three months.

All of this is done to advance the serious business of mating and birthing that takes place in Samaná. The female gestation period is a full year, so calves that are conceived in the bay one year are born here the next; there’s a good chance you’ll see at least one of the babies, which can weigh over a tonne and are light grey. Mothers give birth at two-year intervals and shed up to two-thirds of their body weight while nursing; if twins are born – as they sometimes are – the mother is forced to choose between them, as her body cannot feed them both. The thick milk enables infants to grow at the astonishing rate of over 40kg per day.

Whale watching as a local tourist industry was begun in the 1970s by Kim Beddall, then an itinerant scuba instructor with no formal training as a marine biologist. She’s spent the subsequent twenty-plus years lobbying for government protection of the whales and creating an economic incentive that will protect them should the international whaling ban ever cease. As a result, more than forty boats in Samaná offer whale-watching tours every winter and regulations, again instigated by Beddall, are in place to try and ensure that the vessels don’t harass the animals.