Daniel Radcliffe Says Filming Underwater For Harry Potter Resulted In 7 Seconds Of Usable Footage Per Day

It doesn't matter how big of a fan you are of the "Harry Potter" franchise, there's still no way to comprehend what it was like to be part of the cast and crew, filming these classics for over 10 years. This team had the unique responsibility of properly converting J.K. Rowling's penned fantasy world into a visually stunning reality. While Daniel Radcliffe and the rest of the child actors basically grew up together, the behind-the-camera crew surely had enough work on their hands to fill all the long hours. This especially goes for the set builders.

For fans of the "Harry Potter" books, engineering the magical world of wizards and witches fell into the hands of the reader. But, when it came to making the films, that responsibility was given to the set designers. These were the artists that created the incredibly realistic details of Diagon Alley, Hogwarts, and countless other locations which were initially described in the books.

One of the many crafted locations was that of Hogwarts' Black Lake, featured in the fourth film, "Harry Potter and the Goblet of Fire." In a new interview with GQ, Radcliffe speaks on all the impressive set pieces that were continuously built throughout the shoot and how this specific location, the murky lake, was actually a giant tank that they had to film inside for roughly six weeks.

In the 2005 film "Harry Potter and the Goblet of Fire," Harry is one of four tournament champions battling it out for the Triwizard Cup. The second of three tasks takes place in the murky Black Lake located at Hogwarts. Here, a loved one has been taken from these competitors and chained to the bottom of the lake, guarded by merpeople. Their challenge is to rescue their assigned captive first, without resurfacing from the water beforehand.

Many of the action sequences were filmed below the surface of the water, though in an indoor tank — not a real lake. "I had a logbook of all the hours I had done underwater," Daniel Radcliffe recalled to GQ. "It was really cool." What's also fascinating, is that for a scene that lasted for only a few minutes, filming in the water tank lasted roughly six weeks. And if that's not shocking enough, the amount of actual footage used in the final product is a just tiny fraction of that. "I've heard that we averaged like seven seconds of footage a day, of usable footage," Radcliffe claimed.

Looking back, Radcliffe admits that all those long hours of work, just to get a tiny fraction of usable film, really didn't matter to him at the time. "Those are one of those things that you go like, 'I will never do that again,'" he said. "And if I do, I will be one of the only people who's done it before!" It's clear that those experiences, in addition to being incredibly time-consuming and necessary for the creation of these beloved films, were something those involved will surely never stop appreciating. "It's one of those moments that you look back and I go 'God, that's special,'" Radcliffe said.