Top Ten Memories from Cameraman Simon Reay

10. Filming in a dry suit under the ice in Siberia -- very cold and very claustrophobic. In the show watch to see the water on the lens freezing as soon as the camera surfaces. My hand was in a 5mm glove and it froze around the camera once we were out of the water -- it took an hour for feeling to return. How Bear did this naked I will never know!

9. Alligator swim in the Everglades -- very scary. Bear and I knew there were two gators 20 feet from us ... but it's the ones you can't see that you worry about! Big relief at the end of that one.

8. Toboggan run in Siberia -- Bear and I started on a ledge with an 8-foot drop-off. I tried to keep the camera alongside Bear for the whole 200-foot run ... I didn't, but I did end up in a heap with him at the bottom! Great fun, though.

7. The water jumps from helicopters -- always challenging! I have to jump with the camera at the exact same moment Bear does, otherwise he'd hit the water before I've left the helicopter even at 50 feet. Plus, Bear always says to me, "Don't land on me with that camera!" I haven't ... yet.

6. Rapids -- we've shot so many of these over the three seasons but each time it's different. Trying to stay with Bear in the white water is always tricky, especially in the Lower Zambezi with many underwater unseen hazards.

5. The humidity of Australia was truly unbelievable. It was 45 degrees Celsius (113 degrees Fahrenheit) with 100 percent humidity, which means your sweat cannot evaporate into the air to cool your body as the air is saturated.

4. I loved filming in the swamps of Louisiana and the Everglades. They make you so alert because there is so much life you can't see beneath the water you are wading/swimming in, but you just know there are things down there! This makes the swamps tough to work in, but don't get me wrong, it's so exciting and energizing.

3. The climbs. I don't mind heights fortunately and Bear always seems to want to climb the hardest routes up or down. Good on him! And we try to put the camera right next to him as he's climbing to give the viewer the "Bear's eye" view.

2. In Siberia we had to run for an express goods train that we spotted in the distance. We started running downhill at full sprint towards it across a lumpy snow-covered field. About halfway I lost my balance and went head over heels down the slope with camera on shoulder. Amazingly the camera stayed there during my roll and I ended up on my feet and carried on filming. I honestly thought that was the end of the camera that had lasted us two years. I don't think that shot was used -- what a shame!

1.The crevasse in Patagonia was amazing and very deadly. Crevasses look beautiful and tranquil -- hard to believe that they move at all. But beware! They do move. Bear and I went down two separate ice holes that joined partway to show how hard these are to escape from. Partway down I found myself swinging way too far from Bear; the only way to get to film him was to swing and run horizontally across the sheer ice face on my rope in order to see him in the adjacent hole. You have to trust your crampons and run, trying not to make too much noise in the process because of the fragile ice.