I recently spent two years in the Arctic filming the series Blue Planet. I love being in an environment that hasn't changed for 20,000 years. Of course it's freezing, but it must be a healthy place because you never catch colds.

When I'm filming, I like to really feel how lonely the environment is. Filming underwater involves cutting through thick ice and diving in tied to a line. The person at the other end has to be ready to pull you out fast if necessary.

Originally I was a research diver for the British Antarctic Survey project, but for me science lacked excitement. I'd always enjoyed photography, and whenever camera teams passed through, they encouraged me to watch and learn. I was then able to move into filming in 1985 and have concentrated on Arctic and Antarctic wildlife ever since.

I prefer to be faced with the animals I'm filming. I haven't got in the water with killer whales yet, but I plan to. Of course, it's dangerous if you choose the wrong moment. They're big animals and can move fast, so I'd be stupid to film them searching for food!

I've never had problems with polar bears, although once I was frightened when one tried to get into my tent. Polar bears are bold, clever and dangerous. But I made this one see I wasn't about to attack it - I'm sure it realised I wouldn't hurt it.

When I come home back from my trips, I work in the mornings and spend the afternoons swimming to keep fit. Now I'm fifty, filming is harder. The challenge for me is to continue to deliver high-quality work.

56. In this text, the writer is describing __________.

A. the challenges of the environment he works in      

B. the beautiful scenery of the Arctic

C. the career opportunities in TV camera work.  

D. the difficulties of having to work alone