Hollywood legend Sir Ridley Scott's team has opened up about filming Alien: Covenant in Milford Sound - including setting off a huge fireball.
Producer Mark Huffam tells Mountain Scene a scouting trip was set up at Scott's insistence and he fell in love with the location.
The first trip was scuppered by bad weather but a trip last October cemented its place in the blockbuster.
While Paradise and Mount Earnslaw, near Queenstown, were amazing, he says they didn't make the final cut.
Film Otago Southland boss Kevin Jennings says big budget blockbusters filming here boost Queenstown, Te Anau and Southland.
Jennings adds: "He (Scott) is in the top echelon of directors in the world.
"Having him choose Milford Sound is another testament to the value of the locations we have in Otago and Southland."
Jennings: "It reinforces the benefit of having such a diverse range of world-class locations nearby."
Huffam, who's Northern Irish, confirms the set, including a mock spacecraft, cost more than $4 million and was manned by more than 400 crew.
The waters of Fiordland were chosen for their "spectacular beauty" and pipped other spots from across New Zealand and Australia, after an 18-month search.
Special effects for the big bucks film, due to be released in August next year, included a pyrotechnic fuel-based explosion but Huffam was keeping schtum about the boom.
"I'm sure you can surmise that from the photographs," he laughs.
He isn't the special effects guy, but says the team followed strict guidelines from Environment Southland.
"We had to basically prove to them there would be zero residue from the effects. There were all sorts of method statements gone through and approved before filming started. How he [special effects boss] actually did it is his secret."
The set took four weeks to build.
Filming kicked off on April 6 and lasted about two weeks when Scott was joined by stars Michael Fassbender and Katherine Waterston to shoot numerous scenes.
Scott, the actors and the production team all loved Milford - despite the occasional niggle about sandflies.
"The accommodation was challenging. There was no five-star luxury, but there were no complaints whatsoever and everybody had a great time. That comes down to them being in such a spectacular place."
Milford isn't the only area to get a look-in.
The crew filmed for one day at Fiordland's Eglinton Valley Flats.
Whispers surrounding filming are the nature of the beast, Huffam says.
He hopes that turns into bums on seats when it hits the big screen.
Local spectators, hoping to catch a glimpse of filming, were kept well back.
Environment Southland's permit for the filming included temporary exclusivity to a 1.8 hectare area within Milford Sound's coastal marine area.
Huffam says it's more about responsibility than secrecy.
"It was about keeping people safe, not just from the explosion, there was a lot of equipment being moved around, [some] being flown in by helicopter."
Huffam, who also worked on Prometheus, part of the Alien science-fiction franchise, reckons red tape was justified in an area of such outstanding beauty.
"They were very clear with us - if you are not going to follow the rules then consent is not going to be granted.