These gentle giants are by far the most popular attraction on Utila. People come from all over the world to try to swim with the incredible creatures and, it must be said, the majority of people leave disappointed. One divemaster, who has been on Utila for three years, says he has never even seen one. On the other hand, I got within meters of a whale shark on my very first open-water dive. It's really just a matter of luck.
These fish can be seen at any time of the year, but there are certain months when it's more likely than others. Whale shark season generally starts in February when the animals start to arrive. They usually then disappear for a while and return in late March or early April for a few weeks more. They make their last appearance of the year from August until October, before disappearing again until the following February.
Now these dates are hardly set in stone. The whale sharks' movement follows that of the tiny organisms they eat. Changes in global water temperature and currents have played havoc with whale sharks' travel patterns in the past, and are likely to continue to do so. Also, it's not uncommon for whale sharks to appear out of season. Don't assume that you'll see them just because it's peak time, or that you won't because it's off season. Again, a question of luck.
However, these animals move around relatively slowly. There is no question that your most likely to see a whale shark in the days after one is first spotted. If there's a whale shark near the island, he's likely to hang around for at least a few days. So if you do hear of a sighting, try to get into the water as soon as possible.
Questions of how to safely and responsibly interact should be explained by your diving outfitter, but we'll go over them briefly here:
Whale sharks are filter-feeders, so there's no risk of them trying to eat you. However, their enormous tail can pack a wallop, which is why it's recommended you stay at least four meters away. You should avoid touching the whale sharks, for your safety as well as theirs. Whale sharks are covered with a layer of mucus. By touching them you rub this off, and leave this increasingly rare animal vulnerable to skin infections. Finally, if you are fortunate enough to get into the water with one, try to avoid splashing. This frightens the fish, particularly when large numbers of divers do it. It's likely to respond by diving deeper. This ends your adventure, and it's also bad for the animal since you've interrupted its feeding. If this happens regularly, the sharks have been known to become malnourished. In fact, some Caribbean countries are considering a ban on whale shark diving for just this reason. Swim using only your feet, keeping your feet under the water as much as possible.