on their back to get through. the option that you speak about, the drilling through the mountains to try to get down to the cave, that's finished, as is the option to leave the boys there until the end of the monsoon season. those were the three options a few days ago. they have decided to take the boys out the way they went in. but it is dangerous. dara? >> all eyes are now on that tunnel. thank you so much, bill, from thailand, thank you for that report. let's bring in the u.s. cave rescue mission. i know you are joining us from skype. what is your biggest concern in a rescue mission like this one? >> obviously, the choice of bringing them out using the diving techniques was the least safe one, but, at the time, when we thought they could be sheltered in cave for a longer period of time to give them more