Australian actors Richard Roxburgh & Rhys Wakefield star in Sanctum, James Cameronâs new 3D epic underwater adventure directed by Alister Grierson. Roxburgh plays tough-as-nails master diver Frank McGuire whose dive team, including his 17-year-old son Josh (Wakefield), is exploring the South Pacificâs Esaâala Caves. When a sudden tropical storm forces them deep into the caverns, they must fight raging water, deadly terrain and creeping panic as they search for an unknown escape route to the sea.We sat down with Richard and Rhys to talk about the challenges of being in an action film that was shot largely underwater and often in the dark. They told us about the specialized training they underwent to prepare for their physically demanding roles, how being out of their own comfort zone helped them figure out the complicated dynamics of their father-son relationship, and what they did to conquer the occasional panic they experienced while performing many of their own stunts.  Hit the jump for the full interview.Before reading the interview, you can watch 5 clips from Sanctum here.Question: Can you talk about how you prepared for the physical demands of the role?RICHARD ROXBURGH: There were a lot of specific talents that we had to acquire in a really short space of time, not only to get a general sense of them but to look like we were masters at them. It was being thrown into the deep end literally to achieve some of this with spectacular speed. Some of it was more difficult. Some things were just plain hellish like learning to acquaint yourself with the re-breather when youâd only just learned about scuba. That was hellishly difficult because thatâs a really specialized instrument that relies on a great degree of confidence with the whole environment of being underwater, with being really steady with that and everything that goes with it. And then, there were some things that were specifically geared toward certain stunts that we knew we were going to have to do, and so both Rhys and I had a variety with some of them more complicated than others and none of them pleasant. RHYS WAKEFIELD: Yes, it was funny. We started on scuba diving and all learnt to scuba dive which was really pleasant and that was quite enjoyable, and I thought âOh, this will be a breeze. This is going to be so enjoyable.â And then we had to learn on these re-breathers, which is really advanced technology, and something we had to pretend that was really acting at its finest, pretending that we knew what we were doing.When the two of you first met, were you buddies right off and then you had to turn on the animosity for the beginning of the movie? How did that relationship work?WAKEFIELD: Weâve gotten along right from the start just naturally so we never had any kind of â well unless you were distancing yourself from me or something. I mean, we were very much⦠ROXBURGH: (interrupting) Youâll know when I distance myself from you. WAKEFIELD: Well, there you go, I guess he didnât distance himself from me. No, it was all a very organic experience and I think that we learned and grew to know each other further through the training which was such a big component of this film. We learned all these adventures that we had to go on and you really bond with someone when youâre out of your comfort zone. ROXBURGH: There was quite a bit of that on this film â a sense of the acting department kind of safeguarding itself because a lot of it was so technologically driven and driven just by the specifics of the environments we were in, whether it was white water or underwater or climbing rock faces. There was always stuff being thrown at you and sometimes you feel like some of the key ingredients of whatever the storytelling is could have been swept away with it. And so, there was quite a strong sense of us looking after that. WAKEFIELD: Yes, trying to preserve that father-son relationship especially which we both felt was a real core to the audience following us with the film.In the pantheon of overbearing father figures, Frank at least has the advantage of being right most of the time. How did you guys figure out the dynamic of that relationship?ROXBURGH: Frank is very characteristic, by the way, of the people who do this type of stuff. There is a real kind of military quality that these guys have. Thereâs a steely discipline, and also to do the particular thing that these people do, which is certainly anathema to me, I think it requires an odd Zen self-discipline and also an ability to do what you see Frank doing, which is to let practical reality be the thing that dictates the terms always so youâre not allowed to spend time grieving. If somebody is going to weigh you down, then they need to go. Itâs as brutal as that. Having said that, thereâs a chart that we had to find with the character through the terrible things that happened that was about him sort of softening and accepting that his son not only was a human being but that his son also had skills that he perhaps didnât have and I suppose a sort of flowering of his pride in his son which is an appealing thing for me in the story.One of your characters loves seeing things that no other human has seen before and the other is like who cares, this is crazy, youâre going to kill yourself. What did you learn about yourself in terms of the bravery that goes along with having to train and learn what these real people do?WAKEFIELD: Meeting one of the co-writers, John Garvin, who wrote one of the key handbooks on re-breathers, so heâs a massive dive enthusiast, re-breather enthusiast, he said to me that he had to give up cave diving because it was just a matter of time before he would end up⦠I mean, the statistics are just in play that it was a matter of time before he would never be returning home. Thereâs this sense of adventure and this seriousness that is instilled in these people and I think theyâre constantly looking for that adrenaline rush and that exploration, and yet you see their eyes light up, especially talking to Andrew Wight who the story is inspired by. I canât imagine going down to a dark space and having no idea where Iâm going and not being able to breathe. That doesnât sound overly appealing to me. It definitely takes a certain individual to really feel that theyâre discovering the final frontier that we can on earth. It was interesting speaking with them. I still canât understand it.Since the film is inspired by an actual event, did they model your characters after someone in particular?ROXBURGH: The characters were not ostensibly based entirely on anybody in particular but youâd have to think that Andrew Wight writing this, himself a cave diving expert and I suppose a tough nut, heâs a pretty good model for the character of Frank. It was useful having him on set both as a character type and also frankly as a resource for all of the information that we would constantly need on set â whether it was about handling a piece of equipment or in a spiritual sense like what would you be feeling in this moment.I have to say youâre not only very brave actors but very brave individuals.ROXBURGH: Thereâs a line between braveness and stupidity.On the set, did you ever have a moment where you said âGive me some time. Cut.â? Were there any panic attacks?WAKEFIELD: Yes, shooting the underwater stuff could have gone one of two ways. You have to have a sense of trust and control or it can become somewhat meditative and therapeutic. There was a moment I remember myself where Iâm in the part of the film where I have no breathing apparatus and itâs really a lot of breath holds and my ears started to have this chronic ache and for some reason I couldnât pressurize. I remember just panicking because Iâm trying to find where my regulator is and who can hand me my air and then thereâs canopies of rocks under me and your natural reaction is to want to head up to the surface. So that was a scary moment. I was treading water for a little bit just breathing and trying to chill out and that was my moment. ROXBURGH: There were quite a few moments like that. Quite a lot of the film was spent having to supervise your own mind. For instance, we shot all of the underwater stuff at night which in itself is a surreal enough thing. You get to set, youâre dropped down into a tank in pitch dark in Queensland, then they turn all the lights off, and then the only lighting you have is the lighting that you provide yourself. My last two nights, I had a head cold. I couldnât equalize going down and I was playing in a tight restriction with bleeding from the nose because of the pressure in my head and that was fascinating. That was interesting because also there were these seemingly insurmountable number of obstacles to performance. For example, in that instance, none of us could communicate. When we were doing all the underwater stuff, they didnât have coms so they couldnât hear us but we could hear them on loudspeaker under water. So again, if you had any problem, how do you communicate? It was almost as if, if you have a problem, make it go away yourself quietly. So yeah, there was a lot of mind control.Did both of you go through full PADI certification for this film? And if so, where did you do that and do you continue to dive?WAKEFIELD: I did mine in Sydney, back in Australia at Ship Rock Cove I think it was called. I went on a dive in between the shoot that I didnât tell the producers about because I donât think that was really allowed. I was on holiday over New Years so I was in Fiji on this tiny island. I went diving with sharks for my first dive outside of training. I got out on the boat and the guy said âSo youâve dived before?â and I said âOh yeah, Iâve dived a bunch of times.â Then when Iâm down there, I think I went through 60 minutes of air in half an hour. There were sharks surrounding me. It was amazing but I kept that to myself until toward the end of the shoot. ROXBURGH: Yes, I also obviously did the scuba course and I look forward to scuba diving where you can always see that thereâs a surface above you. WAKEFIELD: And some warm water with some pretty fishes. I think thatâs my kind of thing.What did it mean to both of you to film this in your own backyard Down Under as opposed to other places it could have been filmed like in the Caribbean or Hawaii?ROXBURGH: Well it was handy but also what was appealing was having the characters being largely Australian lends the film a measure of authenticity and also the story is attacked with some rigor. I think that the character I play is really tough. I mean, heâs just a tough, hard man as indeed these men seem to be. Theyâre largely men. I use the word âmenâ in that way. Theyâre mainly men who do this. I admire the way that it hasnât been softened unnecessarily and that the journey to some sort of rapprochement with his son is a difficult one and itâs forged in a horrible terrain of circumstance that happens under the ground surrounded by water.Rhys, how did the experience of being on an Australian soap opera prepare you for a big Hollywood production?WAKEFIELD: I was on a TV show back home called Home and Away which has this incredible turnaround where you shoot an episode a day basically. For me, personally, I feel itâs been the best training. It was like paid training that I got whilst I was still at high school. And thereâs no time to mess up. You really need to get straight into professionalism. I think thatâs a perfect thing for rolling into a film set where there are so many more intricacies and I much prefer the detail that goes into film. It was good. I really cherished my time on that show.How much did you guys interact with James Cameron during the production and how would you typify his influence on the film?ROXBURGH: Well James was there in his capacity as EP so he was really unstressed and he would come in and it was always terrific when he was there. He was a complete gentleman. Of course, he has this ferocious reputation but he was terrific. He is also a devotee of this type of activity and is arguably another one of these types of people who like this kind of frontier work and so he was an interesting person to talk to in that sense as well. Just to try and get to the nub of what it is, why would you do it, heâs an interesting resource for this film in that sense.If you take away the adventure of actually making this film, what was the first appeal to both of you of the actual story behind it?WAKEFIELD: I think the main appeal and what will be a pleasant surprise for audience members is the father-son relationship. That was the most enjoyable part for me as an actor for this piece aside from learning all of the skills that came with it and it was such a physical role and itâs an action adventure film. It was such an important component to get right and to really find the precarious balance between being petulant, and from my characterâs perspective, being too petulant versus being the emotional compass somewhat so that people can really follow the relationship and sympathize with the character of Josh and understand what heâs going through. That was the biggest draw card for me.Richard, a few years ago there was an odd trilogy of films that you did including playing Sherlock Holmes in The Hound of the Baskervilles and that rolled into The League of Extraordinary Gentlemen and then to Van Helsing and all these characters that were based on literary figures. Were you feeling a pull toward literary figures at the time or was that just happenstances?ROXBURGH: No, that was very much happenstance. It wasnât as if I was having a leaning to playing these famous Edwardian literary figures. It just kind of fell that way really.Within the past couple of years, both of you have embarked on fairly new phases of your careers. Are you looking forward to those challenges and what is in the future for both of you?ROXBURGH: Sanctum was smack in the middle of a spate of manic, back-to-back things. I went straight from Sanctum into producing, creating and starring in this series for ABC (Rake) which was fantastic. It was absolutely great. I like mixing things up. I get bored doing the same thing, and obviously with a film like Sanctum, thereâs no risk of that. I donât mean to say that I would never do another film like this. I like the challenge of different things because I directed a film two years ago as well. So I enjoy the movement between all of these things. I just finished a stage play in Sydney. For me, itâs important to get variety because I find that is very good nourishment. My main priority at the moment is to get back to my family and to spend some time with my boys, one of whom was conceived during Sanctum, and have some quality time. WAKEFIELD: Iâm based here now in L.A. so Iâve been back and forth for a little while and now Iâm here. I really donât know what to expect. Itâs exciting and I hope that the film is well received. There are a few projects that are in the works but weâll just wait for confirmation and see how that all goes.Sanctum opens in theaters on February 4th.