Whale sharks gather to gorge on plankton and fish eggs. Sometimes they are groups of young males, others are more mixed. The largest known gathering is off the Yucatan in Mexico with nearly 1,000 whales sharks converging. Other involve barely a dozen gathering to feed on the surface. There are reports that some aggregations include pregnant females, but to date no mating has been observed - the presence of the pregnant females would suggest breeding grounds may well be near some hotspots. Scientists know little about the largest fish in our oceans and the full function of these aggregations are a mystery. Here is our Big 12 - if you know of other whale shark hotspots just add to the list…

1) Ningaloo, Western Australia

This is the grand daddy of whale shark hot spots with divers and snorkelers revelling in close encounters since the 1980s. A recent study by the Australian Institute of Marine Science-University of WA said nearly 20,000 tourists a year participate and the business generates more than AUS$6 million a year (£3.8m). The peak time is around May.

2) Seychelles

Researchers on micro-light planes spot the sharks as they gather off the main island of Mahe and direct the dive boats to where they are feeding during October and November.

3) THE GULF of TADJOURA, Djibouti

This aggregation attracts young male fish - some around 2.5m in length and scientists guess that they could be as young as 6 months to one year. A new born whale shark is about 60cm - but there is little reliable data about growth rates. The mean size for the fish off Djibouti is 3.7m  - clearly a whale shark primary school! The peak time for the gathering is January.

 4) AL-LITH, SAUDI ARABIA, RED SEA

Recently discovered by researchers from the Woods Hole Oceanographic Institution and from the King Abdullah University in Saudi Arabia this aggregation on an isolated reef consists of hundreds of young whales sharks  - unusually it is a 50/50 mix of males and females.

5) Gladden Spit, Belize

For 10 days after the full moon during the months of March, April, May and June thousands of snappers spawn around Gladden Spit in Belize and whale sharks gorge on the feast of fish eggs in clear blue water.

6) Quintana Roo, Yucatán Peninsula, Mexico

By number of animals, the Yucatán Peninsula is arguably the largest and most important known aggregation area for whale sharks anywhere in the world. At least two aggregation sites are present in this region: the green water site north of Cabo Catoche and the blue water Afuera location. As many as 1,000 whale sharks gather in the area from May to September each year.

 7) Afuera, Yucatán Peninsula, Mexico

68 whale sharks, a tourist boat and two swimmers - aerial photo taken in 2009

This more remote aggregation of whale sharks was recently identified farther to the southeast of Quintana Roo ( Afuera is Spanish for outside ) in the offshore waters between the Isla Contoy and Isla Mujeres. Aerial surveys in 2006 identified a total of 480 whale sharks in the area. The fish are thought to be feeding on fish eggs in the Afuera aggregation and plankton in the Quintana one.

 8) Al Shaleen oil field, Qatar

Research student  David Robinson from Heriot-Watt University in the UK discovered this major aggregation within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. In the summer months, more than one hundred and fifty whale sharks have been recorded feeding in the warm surface waters of the Arabian Gulf. Although the sharks have been observed by local fishermen and offshore platform workers for years, the magnitude of  the aggregation has only just recently been realised. It is particularly unexpected because the sea surface temperatures can reach up to 34 degrees celsius in the summer, above what was believed to be the comfort zone of whale sharks.

9) Ari Atoll, Maldives

A regular star attraction on liveaboard trips in Ari Atoll in the Maldives is the gathering of whale sharks each summer. Mainly young males.

10) The Galapagos Islands

The overwhelming majority of sightings for the whale sharks gathering off Darwin island in the northern parameters of the Galapagos Marine Reserve are for pregnant females. Tagging projects reveal that the females then head further out into the Pacific off the continental shelf.

11) DONSOL, LUZON, the Philippines 

A popular spot to find whale sharks feeding around March and April - now only snorkelers in the bay.

 12) OSLOB, CEBU, THE PHILIPPINES IN MARCH,