Hong Kong is one of the world's busiest ports, but as a growing number of container ships compete with fishing boats for space in an ever-shrinking harbour, a spate of accidents has raised fears for maritime safety.

The city, whose name means "fragrant harbour" in the Cantonese dialect, is as famous for its crowded shipping lanes as it is for its bustling streets.

But a fatal collision between a local ferry and small pleasure boat in October 2012 left 39 people dead and sparked an investigation that discovered a "litany of errors" contributed to the tragedy.

Since then, a number of other incidents -- including two high-speed ferry accidents that injured scores of passengers, and the grounding of a large container ship -- have left those who ply Hong Kong's waters worried.

Hong Kong's glittering skyscrapers are built around the iconic Victoria Harbour, where thousands of people criss-cross the waterways that separate the mainland and the city's islands daily.

Annual vessel arrivals in the southern Chinese city have almost doubled since 1990 to almost 200,000 in 2013.

Much of this increase is due to the construction of ports in the neighbouring Chinese trading hub of the Pearl River Delta, which has led to more container ship traffic. Hong Kong itself is home to the world's fourth-largest container port.

Kwok Mook-kiu, 69, who has worked as a small fishing boat or "sampan" operator for more than 30 years, said it is increasingly difficult to navigate a safe path.

"There are so many more ships now. If a big cargo vessel passes by, I will just stop and wait until it is gone," she told AFP.

- Intense traffic -

"Few ports have the same intensity of marine traffic, or range of vessel sizes," said Richard Colwill, who has worked as a marine planner in the city for 17 years.

Around 1,000 container ships and high-speed ferries use the city's waters each day, said Colwill, sharing routes with fishing boats, tug boats, yachts, cargo barges and local ferries.

But while he believes the waters are safe, the increasing number of ferries means that if there is a collision, the potential for casualties is greater.

"Should an incident occur, we are having more serious consequences because of a higher proportion of ferries within the traffic mix," said Colwill, managing director at infrastructure consultancy BMT Asia Pacific.

In May, a high-speed ferry collided with a cargo ship, injuring more than 30 people, and in November last year a high-speed ferry crashed into an unidentified object, leaving 87 hurt.

That incident also highlighted the problem of rubbish strewn across the waterways.

Tony Yeung, a former captain who now heads a local marine training institute, says obstacles as large as beds and refrigerators would force him to make a detour on busy sea routes.

"When you are riding a high-speed ferry and you run into any of them, it can be very serious. When you go around them quickly, there may be other ferries beside you that you can crash into," he said.

- Shrinking harbour -

Boat operators say there is also a problem with land reclamation, which has seen Victoria Harbour shrink over the decades to create more space in a densely packed city.

"The harbour has shrunk. The government wants land everywhere," sampan operator Kwok said, adding that this increases risks.

But the government's marine department defends its safety record, saying the number of collisions has fallen, from 327 in 1995 to 183 in 2012.

"The average number of collisions is about 170 cases in the past five years. Most of the cases were minor in nature," a marine department spokeswoman told AFP, describing there to be about 135,000 passenger trips made daily on local passenger vessels.

The probe into the 2012 tragedy found safety measures were not enforced by inspectors for the department, described as "understaffed and underfunded" for the past decade by Paul Zimmerman, CEO of Designing Hong Kong, which campaigns for better planning and policies in the city.

"The report thereafter basically found that in the last 20-odd years, the marine department adhered to some very casual attitudes and has not put good effort into maintaining a comprehensive inspection system," lawmaker James To, who assisted the families of the victims, told AFP.

The department, which said it has "strengthened" ship inspections after the disaster, has proposed improvement measures including a requirement for large passenger ships to carry better tracking and communication equipment.

Meanwhile, those who spend every day on Hong Kong's frenetic waterways say vigilance is key to survival.

"Of course I am worried about accidents, I am always afraid," a 72-year-old ferry captain surnamed Lai said.

"Sea traffic is busier now... just like crossing a busy road, you have to pay extra attention."