The Whales we dive with are south pacific Humpback Whales (Megaptera novaeangliae) which follow annual migration routes between the southern polar Antarctic waters during summer and various tropical areas during winter.

The kingdom of Tonga is one such special area, with pristine warm waters offering the perfect home to many pods of Whales each year from July through October for mating and calving.

Humpbacks are baleen Whales, with hundreds of dark baleen "plates" hanging from each side of their upper jaw with which to filter huge amounts of water for food. Each adult can eat over 1300 kg (about 1.5 tons) of krill (small shrimp-like crustaceans) and small fish a day!

Adults can grow to over 18 m (about 60 feet) in length, about 50 tons in weight and to an estimated 95 years of age.

The calves when born are usually 3-4.5 m (about 10-15 feet) in length and can weigh over 900 kg (about 1 ton). Nursing at frequent intervals on their mother's rich milk when young, they gain around 1 kg (2.2 lbs.) every hour. During this nursing period in tropical waters the mothers can lose up to 1/3 of their body weight as they do not actively feed other than opportunistically if they chance upon a shoal of pilchards or the like.

Humpback calves do not actually suckle from their mothers but have the rich stream of milk squirted into their mouths when they are quite close, and are weaned onto solid food after about a year.
Whilst adult females can produce a new calf every year, the new mothers avoid mating until their existing calf is one year old - this allows the attentive mother to look after this calf through a two year period, affording it a much better chance of survival.

Although both male and female Humpbacks are capable of song, the male is the main singer of the family. During mating season males will sing complex, organised songs with distinct themes and melodies for up to 20 minutes, sometimes repeating the song continuously for hours at a time. Whalesong can be heard over hundreds of kilometres away (underwater) and appears to change gradually from year to year.

They are also well known for hurling their massive bodies completely out of the water in magnificent displays called breaching. Three strokes of a Humpback's tail is all that is needed to launch 40 tonnes of Whale clear of the water.

Theorised to be associated with courtship or play activity, it is in fact a method of dislodging the huge barnacles that attach themselves to the Whales whilst they are in the Antarctic. These barnacles do not survive in the warm tropical waters and the Humpbacks clear their skins of these parasites in this most spectacular fashion. Young calves engage in the breaching as well, emulating their mothers in this survival skill.

During these breaching displays the Whales slough, or lose some of their skin. Scientists are now collecting this shed skin for DNA comparisons and research.

With the turn of the 21st century, even though Humpback Whales are found in every ocean on earth and their numbers have appeared to be slowly and steadily growing, they are still considered an endangered species.
In the 1960's estimates of their numbers were as low as only a few thousand in total, and the International Whaling Commission (IWC) gave them world-wide protection status in 1966.
Original global population estimates hundreds of years ago are of the order of 150000 or greater, whilst at the year 2004 estimates range from 20000 to over 30000 and climbing - which is great to see.