Sydneysiders have been mesmerised by colours and music as this year's Vivid festival lights up.
The annual lights, music and ideas festival began at 6pm on Friday with the illumination of the Sydney Opera House, transfixing viewers with a futuristic light and music display featuring imaginary sea creatures lurking deep in the harbour and shimmering plant life.
With a crowd of more than 2.3 million expected over the next 23 days, police have reassured Sydneysiders they will be out in force - on land, in the water and in the air - especially following Monday's UK terror attack that killed 22 people.
"If we believe a package is suspicious - a backpack or whatever - we will undertake whatever is necessary to ensure that package is rendered safe," NSW Police acting assistant commissioner Michael Fitzgerald told reporters in Sydney on Thursday.
Mr Fitzgerald said after vehicles were used as weapons in Nice and London the force worked with the counter-terrorism command to create "vehicle mitigation strategies" during the event.
"The public will see water-filled barriers and police cars blocking access into Vivid Sydney and that is for their protection," he said.
With a hoped-for crowd of 2.5 million, NSW Premier Gladys Berejiklian says the state is ready to "welcome even more visitors" to enjoy the array of colour and creativity and give the region an economic boost.
"We're hoping to surpass last year's massive $110 million injection into our state's visitor economy and going on indications from hotels and major attraction bookings, we're on track," Ms Berejiklian said in a statement on Friday.
NSW Major Events Minister Adam Marshall says this year will be the "biggest and best ever" festival with public safety a top priority.
"Rest assured, you will be able to enjoy Vivid again this year and continue to be safe because the police will be out there in larger numbers than ever," Mr Marshall told AAP.
He encouraged people to get out and stroll the streets of Sydney during the festival and promised: "It will be something different, it will be bigger and better and you will continue to be amazed and have that wow factor."
For 23 consecutive nights, music and lights will dominate the city, featuring the largest interactive light display in the world, multimedia sculptures of the giant Port Jackson Shark, imaginary creatures and musical performances.
