More than 30 dolphins were seen swimming near the Dai Lanh in Dong Hoa Town in the southern province of Phu Yen on May 14.
The dolphins, each over two metres long, were seen by a group of tourists in the area, who started to take photos and record videos of the beautiful animals.
A tourist guide, Van Duy said they saw the dolphins swimming in the area for about 20 minutes.
I've never seen so many dolphins," Duy said. "Many of the tourists were very excited to see them."
Head of the Dai Lanh Lighthouse Station, Nguyen Trong Thao, said that dolphins usually appear in calm water.
“We saw a large group of hundreds of dolphins near the Mai Nha Islands in Tuy An District three years ago," Thao said.
Last year, dolphins also appeared in some areas in the neighbouring province of Khanh Hoa.