Fung Shiu-chung struggled to help passengers survive as he clung to the hull of the boat waiting to be rescued.
Mr Fung had gone on the tour with seven members of his family, but feared last night that some had not survived.
He said: 'We arrived at Manila Bay shortly before 4 pm. It was the first sightseeing tour on our programme.
'The boat was trying to sail out of the bay along the shore when, all at once, it just overturned. It seemed to lose balance and completely capsized. It was very sudden.
'Both decks were full of people. The situation was chaotic. We didn't know what was happening but all at once we were being thrown into the water,' he said in an interview with Commercial Radio.
The wooden cruiser was close to the shore and other ships went to the rescue. Mr Fung said: 'I was lucky. I managed to grasp hold of the ship while others were sailing over to help. People like me who could swim were holding on to those who couldn't and clinging on tightly to the hull of the overturned ship.' Crews on motor sampans threw ropes and life jackets.
Asked if he was hurt, Mr Fung starting crying, saying: 'Yes, but I was only slightly injured. I know some of the others on the tour have died.
'It's only the first day of the tour. I didn't know them, but it's so terrible some of them died so suddenly. There was a 60-year-old woman on the tour. I'm sure she hasn't survived. And the parents of one of the children on the tour have just arrived at hospital hoping for a miracle.' It was Mr Fung's second visit to the Philippine capital.
Mr Fung, who stayed at the hospital to act as interpreter for relatives who could not speak English, said: 'This experience is too horrific. My brother-in-law is still missing. I don't know where he is. I hope he will be rescued by others. Maybe he's been taken to the naval base.'