Its arrival has left residents stunned by its height and many trappings, which include a hangar for its two helicopters and a submarine, which is yellow and can fit up to 10 people.

"It's very large but I wouldn't think it will upset anyone, it's just such a fabulous boat. I haven't seen the submarine yet, but we've all seen the choppers," Point Piper local Virginia Rundle said.

It will be one of 3000 vessels catching the evening's fireworks displays, which will attract more than 1.6 million viewers to the harbour shores, according to City of Sydney Council estimates.

It's not the first time a large ship has bobbed off Point Piper during the New Year celebrations. In 2012, Royal Caribbean cruiser Radiance of the Seas moored at the same buoy during an unexpected stopover in Sydney to avoid Cyclone Freda.

While it is smaller than a cruise liner, Octopus has many of the same features such as a swimming pool, juice bar and medical centre, as well as a cinema and recording studio.