Even if you've not seen his indie hit Open Water, odds are that you've seen the work of director Chris Kentis. Before striking gold with his shark tale, he edited trailers - from Boogie Nights to Gangs Of New York. Here he reflects on turning a labour of love into one of the most profitable films of 2004...

You were shooting Open Water for two and a half years. How difficult was it to maintain your enthusiasm throughout this time?

The biggest problem you have is to maintain your focus and passion for the movie. You're working for so long, you have to be careful not to lose track of where you are. One of the big problems is you lose objectivity when you're working on a movie for such a long period of time. At the same time, the problems I had with this are not that different from those facing other filmmakers. Regardless of whether you're making an independent film or Hollywood film, most films take a minimum of two years. In a way we're par for the course. And that's why it's important to choose something you're passionate about. One thing about the way that we were working - that's me and my wife/partner, Laura Lau - is that you have to be really, really tenacious and really disciplined. There's nobody hounding you, no distributors, no financiers - these people aren't breathing down your neck. You could very easily let the time pass - nobody cares whether you get it done or not.

Was the version we see always going to be the way the movie ends? Because it's hardly your typical Hollywood ending...

That was always going to be the ending, because it is based on true events [an Australian couple were abandoned at sea in 1999]. Overall it really is the film we set out to make. The first draft of the script I banged out in about six days, and the shooting script came together very quickly as well, and that's the spirit of how I want to make all of my movies in the future. However, it's important to be open to suggestions from other people but also open to what presents itself when you're shooting a film. Don't be too rigid: you certainly have to have a game plan and be prepared and know what you want to say and what the ultimate point is, but at the same time be open for possibilities. I'm an editor by trade - I work on trailers - so I see a lot of movies go through various stages, and it's an evolutionary process, a process of constant refinement. In our case, the very opening of the film was something that we wrote right near the end; that was the last thing we shot.

When the film hit Sundance, people called it Jaws meets The Blair Witch Project. But what was your own pitch?

The Jaws/Blair Witch thing definitely gave me cause for concern. It's flattering to be compared to two such successful films, but I do think it sets up expectations in the mind of the audience that are not right - the goals of those two films were very different to ours. First of all they are both very different films in themselves. I can understand the comparisons to Blair Witch - unknown actors, low-budget and shot on video, screening at Sundance. And I don't think you've been able to see a shark in the water since 1975 and not have someone compare it to Jaws, which is a brilliant piece of entertainment. But we didn't really see this as a shark film or a horror film; it's much more of an existential piece in our mind!

My goal on this movie was to capture this story in the most realistic way possible, and to tell it through the point of view of these two characters, hoping that audiences would put themselves in their place. That way we could raise a lot of questions about how modern human beings are just living our lives in a small kind of bubble where we're forgetting that we're just part of a much bigger system; there's a certain arrogance we have towards the environment. We get caught up in a lot of small ridiculous things with the people we share our lives with, people we love. We take so much for granted.

When Steven Spielberg made Jaws he inadvertently found success because he had to hide the naffness of 'Bruce', his mechanical shark. You didn't have that problem, though, because you were using real sharks. What was that like?

We shot for about two days - probably one and a half given the bad weather - and we hired [shark wrangler] Stuart Cove, in the Bahamas, who's one of the best in the business for working with sharks. It was quite shocking for me that some of the press described our use of real sharks as a gimmick. When dealing with that element of the story we wanted to make it as real as possible, so if it was possible to work with sharks in a safe and responsible way, then that was the obvious choice. I've been a scuba diver for about ten, 11 years and I've swam with sharks often. One of the big advantages working with Stuart is that these are wild sharks, they are a dangerous species, but he's worked with this population of sharks for over 15 years. He's been in the water with them practically every day during that time, and he really understands their behaviour. So we listened very carefully and worked to the strict parameters that he set up. It was a very controlled environment, which is exactly what you want - because obviously it's dangerous when you're in the water with a seven foot animal with sharp teeth!

The film has taken over $30 million in the States and been distributed worldwide, so how have things changed for you?

Obviously monetarily we were rewarded well - way beyond what we would have expected - and Hollywood has opened its doors and there's a whole new world of opportunity available to us now. Just in the last few weeks we've been able to catch our breath and decide what we're going to do next. I've got a stack of scripts in front of me right now that I've got to start reading. The main thing is, making Open Water was a fabulous experience for me. Long before we got to Sundance, and before we expected anything much to happen, I remember thinking: If this movie goes nowhere, I don't regret a day of it and the whole process.

We've got five projects right now that we're going forward with - some of them larger-budget studio pictures, some are self-generated that Laura and I are writing - but there's a long way to go. The one thing is that they are all very different from Open Water.

Would you continue to shoot on DV in the future?

I think most stories are best told with the look you get shooting on film and shooting with a crew. That said, if I could find the right story I'd do it again in a heartbeat. The gap between video and film is closing. Even since we made Open Water, the cameras that are avilable now in comparison to the ones we shot on three years ago [Sony PD-150s and VX-2000s] are astonishing. Technology really is advancing like lightning, which makes the idea of shooting on video all the more viable - especially when you look at the guys who are doing it now - everyone from Danny Boyle [on 28 Days Later] to Michael Mann [Collateral].

What advice would you give to someone who's starting off, armed only with a camera and a lot of enthusiasm?

First of all, you have to find a story that you're really excited about. But it also depends if we're talking about a feature-length movie or a short. I'd say, go out, look at what your resources are, what you have to work with. Take these assets and then don't worry about the perceived limitations. You have a camera, you have the tools. You're one of the first generations to actually have that. But you have to do it for reasons of loving the process and learning. If you want to make a feature, understand that each film is part of the process of learning to be a better filmmaker. If someone's looking to make a movie to get rich quick, there's a lot faster ways to do it! That was the last thing on our minds, even if we did hit the lottery with it eventually for whatever reasons. It's a very exciting time to be a filmmaker, so go out and start making movies.

Open Water is out to buy on DVD, and to rent on DVD and VHS, from Tuesday 27th December 2004.