Every year, some 85% of the Atlantic humpback whale population passes through the warm waters north of the Dominican Republic, turning the area into one of the world’s best whale watching sites. From late December through March, thousands of whales from North Atlantic feeding grounds—from the Gulf of Maine to the Norwegian Sea—descend to the Caribbean to mate and give birth.

Daily at that time of year, dozens of small boats filled with tourists from around the world cruise the waters in search of the massive mammals, which reach 52 feet in length and can weigh up to 79,000 pounds. Rarely do the whale watchers go home disappointed.

“They’re one of the best whales to observe because they’re so naturally curious and playful,” says Leida Buglass, a marine biologist with the Center for Conservation and Eco-Development of Samaná and its Environs (Cebse), a nonprofit here.

That curiosity was on display on a cloudless March morning as a six-week-old humpback whale calf and its mother rolled and dove, drawing applause from passengers aboard a handful of boats.