Two tourists were killed and dozens were injured when a boat capsized amid rough seas in Bali.

The holidaymakers, including at least five from Australia, were riding the fast boat called Dolpin II when they were struck by large waves off Sanur Harbour on Tuesday.

The vessel flipped over throwing the 80 people onboard into the sea, some 300 feet (100 metres) from the shore at around 3 pm local time.

Locals scrambled to save the dozens of struggling passengers before rescue personnel arrived with inflatable boats.

Footage shows emotional tourists, including a woman seen covered in blood, being escorted back onto the shore as more boats were dispatched to search for missing people.

Aprianus Hangki, head of the Class II Benoa Port Authority and Harbormaster Office, said the Dolpin II left Nusa Penida island with five crew members and 75 passengers, including five Australians, onboard.

One Indonesian crew member remains missing.

He said: 'There are 73 survivors. Two people have died, and one person is still being searched for.'

The casualties were identified by authorities as Shio Quo Hong, 20, and Hanqing Yu, 37, both from China An Indonesian worker, I Kadek Adi Jaya Dinata, 23, was still missing.

I Nyoman Sidakarya, head of the Denpasar Search and Rescue Agency, said 14 injured passengers, including the Australians, were taken to a hospital.

He said: 'We are continuing to gather information regarding the number of passengers and their current condition.'

Boats and ferries are a common mode of transport in the archipelagic nation of Indonesia, which has more than 17,000 islands. Maritime accidents are often caused by poor weather and lax safety standards.

On July 15, a boat capsized off western Indonesia during poor weather. Eleven were initially reported missing and were later rescued.

While on July 3,the KMP Tunu Pratama Jaya ferry sank off Bali, killing 18 and leaving 17 missing. There vessel was carrying 65 people when it sank just 30 minutes after departing from Banyuwangi Port in East Java.