From July to October, humpback whales migrate from Antarctic feeding grounds to the warm waters of the Vava'u Group to breed, give birth, and nurse their calves. Tonga is one of the very few countries that permits swimming with humpbacks under controlled conditions, and Neiafu is where most of the licensed operators are based.
The standard format is a small boat (usually 6–10 people plus a guide) that searches for whales in the morning and afternoon. When a whale is located, the guide enters the water first and signals whether an approach is appropriate. Calves with attentive mothers are often the most tolerant of human presence. The encounters are quiet and completely different from any other wildlife experience: a 40-tonne animal hanging motionless in clear blue water ten metres away from you is genuinely otherworldly. Book well ahead for July and August; the season fills quickly and the number of permitted operators is limited.