It is believed that it might have been the first white whale to be spotted in Thai seas.
Yutthapong Damsrisuk, chief of Hat Nopparat Thara-Mu Ko Phi Phi National Park, said he had seen the clip captured by a foreign tourist of the white whale.
The whale was seen briefly under shallow water before it dived and disappeared.
Yutthapong did not say when the clip was recorded.
He said officials could not yet establish the whale species.
It was the first white whale spotted in Krabi and might even be the first one for Thailand, he said.
He said he had instructed park officials to check the location where the white whale was spotted and to warn tourist boats to move with caution in the area.