Sometimes boats converged on whales and there was danger of whales being chased.
Sri Lanka is perhaps the easiest place in the world to see blue whales according Gehan de Silva Wijeratne, a wildlife author who also helped promote Sri Lanka as an eco holiday destination while working at Sri Lanka's Jetwing group.
De Silva Wijeratne has written that the narrow continental shelf in parts of the south and east coast has allowed whales to come very close to the shore in the annual migration across the Indian Ocean.
De Vos warned that if whales stopped coming close to the shore the industry would also lose out as boats would have to travel further out, making it more expensive and time consuming to see a whale.
Marine biologist Asha de Vos told a conference on marine tourism in Colombo that there was a danger of some whale watching boats disturbing and scaring off whales which now come very close to Sri Lanka's shores.
Sri Lankans became more aware that whales came very close to the i