Some of them are almost breath-taking. Having been trained to quite basic standards - think British Army (black and white only) - i envy these photographers who have the time, imagination, patience, wherewithal (and, dare i say it, luck) to produce such beautiful images.
From a personal point of view, i think the above water/underwater shot is just about the best.
I would be hard pushed to choose a favourite but I was thinking about what fascinating things go on around the world. Wonder if it's an everyday occurrence to see bears walking down the street.