A historic passing on Sydney harbour tonight signalled the beginning of Royal Caribbean International’s Explorer of the Seas’ residence in Sydney.

There were fog horns and fire ships as Explorer’s fellow Sydneysider, Voyager of the Seas, passed on her way out of the harbour.

And thousands of passengers on each ship cheered from their balconies. It was an awesome sight.

Earlier, Explorer’s arrival was brought forward by the need for a medical evacuation to St Vincent’s Hospital.

The massive vessel arrived just after 1pm with a party on the foredeck and a surfer on the Flow Rider with the best view of the Opera House.

She rode at anchor off Taronga Zoo until the historic crossing five hours later.

The two ships bring almost 10,400 passengers and crew and almost $1.6 million into the Sydney economy in passenger spend on this one day alone.

“With over 10,000 people on board the two ships, it’s the equivalent of having the entire population of Byron Bay out on the harbour at one time,” said Adam Armstrong, commercial director, Royal Caribbean International.

“We’ve invested US$160 million in makeovers on both ships in recent years and the result is two spectacular cruise ships offering the biggest choice of incredible Australian-first features including ice skating rinks, exceptional dining options, Broadway-style shows, 3D cinemas, completely refreshed public spaces and staterooms, rock climbing walls, full size sports courts and the Royal Promenade – an indoor street running the length of the ship with shops, a cafe and bars.”

At a whopping 138,194 gross tons, 311 metres long and 38 metres wide, Explorer of the Seas takes the crown of Australia’s largest cruise ship from twin sister ship Voyager of the Seas.

During her five month season Explorer of the Seas will inject almost $44 million into the Australian economy including almost $41 million in Sydney in passenger spend alone.

Explorer of the Seas joins already revitalised sister ships Voyager of the Seas, Radiance of the Seas and Legend of the Seas making the Royal Caribbean fleet the newest and most feature packed ships sailing in the region – a total investment of more than US$280 million.