I WAS EXCITED – photographically and in terms of the sheer experience of the interaction. Perhaps I was also just a little anxious about getting into the water with several of the biggest fish in the world while they were being fed.
In the end, however, it was to be an encounter that completely changed my presumptions of the behaviour, and of the character and sensitivity, of these animals.
Cenderawasih Bay off north-west Indonesian Papua – we had been sorted into two groups of eight by our guides and thoroughly briefed.
I didn’t want to over-reach into the comfort zone of the animals, and a bit of me didn’t want to inadvertently drift into the wrong spot while I was concentrating on my f-stops, and thus earn myself a bump or a thwack from a 5-tonne fish.
So I (all of us, really) started with kid gloves, holding back, moving cautiously.
This was an unusual whale shark encounter inasmuch as the site is one of only three places where whale sharks are baited (the others are Donsol and Oslob in the Philippines).
Shark feeding encounters exist all over the world for the toothy reef sharks, but here the filter-feeding whale sharks are drawn in by fishermen chumming the water.
They pour fish over the side of the bangka, the fishing platform. The huge fish come right up with their cavernous letterbox mouths and suck at the surface, pumping their huge gill-chambers and drawing down a whirlpool, pulling the fish with it. They were Hoovering.
In their eagerness to get the fish the sharks were jostling, nudging and pushing each other without restraint.
But it soon became ludicrous that I was being careful to keep clear and not to disturb these huge, powerful creatures. They moved with a smooth, elegant grace that stills pictures struggle to capture.
Almost imperceptible movements of the fins and tail would have them gliding in fast. And they were knocking each other out of the way pretty solidly.
But not us. We tiny, clumsy humans were keeping a respectful distance but they would come in and swing rather close to us.
It started to dawn on me that they would – without fail – arch their bodies away at the last second.
Before long I simply knew that the enormous tail swinging my way would curl just clear of me.

I RELAXED, AND TRUSTED them to be in control of the encounter, never having dreamt that it would be possible to surrender this dance to a giant fish.
They lined up, and as I was photographing one, another one cruised up beside me, patiently waiting for me to notice and move aside (while framing for the next picture, of course).
I was really taken by the interaction, by the sensitivity of the whale sharks towards me as a clumsy human diver. I have been lucky enough to dive many of the best sites all over the world, and this was one of my best-ever dive experiences.
I surfaced and must have had a look on my face, because our guide Diana just smiled. I asked the question and she said yes, all the guides have the same feeling – the sharks actively manage the encounter, sensitive about these odd, clumsy little creatures.

Whens & whys: Predicting gatherings
Whale sharks being rather big, getting enough food to fuel that body is a constant preoccupation.
However, they are also incredibly efficient travellers and forage extremely effectively, so migrating thousands of kilometres a year – distances that would be impossible for most animals – for concentrations of food is not a problem for them.
Like their distant cousins the basking sharks, whale sharks feed by straining their food using comb-like structures ahead of their gills. They filter the water for swarms of small (often tiny – smaller than a grain of rice) but extremely oil- and protein-rich animals or eggs.
By far the oceans’ greatest food source is copepods – the tiny crustaceans that are the most abundant animals on the planet.
Unlike the basking sharks, which thrive in richer, colder waters with abundant seasonal supplies of copepods, whale sharks live in warmer seas.
Your best bet is to look for surface seas that are 25°C or warmer, but these are effectively ocean deserts, almost devoid of nutrients over vast areas.
Dense copepod aggregations are few and far between in the tropical seas in which whale sharks live.
So whale sharks become dependent on the few oases in these vast ocean deserts, most of which are seasonal. Reef fish and the coral reefs themselves are two such oases, building up nutrients over time and then spawning oil-rich eggs – far denser concentrations of calories than can be found in most tropical seas.
These bounties of food are released for brief, synchronised periods, often once a year. The whale sharks arrive to feed on the spawn, or sometimes on the smaller spawning fish themselves.
In other places with high tidal ranges and nutrient upwellings the tides gather seasonal aggregations of copepods dense enough to be attractive to whale sharks at certain times of the year.
Cenderawasih Bay is unusual in that the bounty of food was natural but has become artificial – fisherman’s catches now keep the sharks interested year-round.
It’s an exciting time for whale-shark research, because we’re beginning to get an understanding of why and where they go.
We still have a lot to learn, but the listings that follow overleaf are some good times and places, with a few best guesses as to the drivers for most of the reliable whale shark aggregations – a whale shark calendar.

Western Indian Ocean

January-May Whale sharks, particularly young males, are seen around some of the southern Maldives atolls as winter monsoon currents sweep in from the south-east.

February-May Whale sharks seen off Gujarat in western India.

April Seen off the Seychelles as the monsoon currents reverse.

July-October The summer monsoon brings cold upwellings from Somalia to Yemen and Oman, driving a massive plankton bloom and attracting some whale sharks. It is one of the few places where cold nutrient-rich upwellings combine with warm summer surface conditions. As the rich waters of the Somalia upwelling system wash over the Maldives’ Baa atoll and wraps around the bottom of India to Tamil-Nadu off the east coast, whale sharks gather to feed in these areas.

July-November For the southern winter, some whale sharks gather off the Seychelles.

October Inside the Red Sea off Djibouti large numbers of young whale sharks are gathered.

October-January Whale sharks, mainly sub-adults, are found off Mozambique, south as far as Sodwana Bay in South Africa (until March) as the spring bloom starts there, across to Madagascar (particularly December) and off Tanzania and Kenya. They seem to prefer areas with large tidal ranges, where vertically migrating copepods are dragged into concentrations in bays and tide-lines by water movements

Eastern Indian Ocean

February-May As the north monsoon winds arrive, whale sharks gather around the Andaman Islands.

February-June Gatherings around north-eastern Indonesia and the eastern Philippines, arriving in numbers of Donssol and Lankayan for the next couple of months, brought in by the zooplankton, sardines and mackerel.

Late March-June Western Australia's Ningaloo reef area is as warm as it will get. Corals spawn just after the full moon in April here and in a few other areas of the eastern Indian Ocean, and whale sharks arrive to feed on the ensuing food bounty.

August-September The south monsoon brings nutrient run-off. Fish larvae released off west Timor attract whale sharks this month.

August-April Peak months around Papua New Guinea.

November-early January Around Christmas Island red crab larvae are swarming, attracting whale sharks.

Tropical Atlantic/Caribbean

January Whale sharks start to arrive off Honduras.

March-May The Bay Islands and Belize attract whale sharks in numbers. Cubera snapper are gathered in spawning aggregations off Belize’s Gladden Spit, and the spawn seems to be what attracts the sharks.

June-September The northern Caribbean is warming up for the spring. Off Holbox Island off the north of Mexico’s Yucatan Peninsula, the Bay Islands, Belize and Tobago several hundred whale sharks gather, feeding as bonitos (July and August) and then corals (September) spawn.

East Pacific

April-October (especially July and August): Large adults gather off the Galapagos’ northern islands, particularly Wolf and Darwin

May-June Whale sharks feed inshore in the south-western Sea of Cortez

August-October In the Sea of Cortez whale sharks gather in the north in August.

September-October The surface seas are cool enough for upwellings to feed the surface seas, and the sharks feast on copepod blooms at tide-lines and at the edges of basins and seamounts.

October-November In the northern and central Sea of Cortez the whale sharks continue to feed on copepods, heading south, and will start migrating out of the sea the following month.