Dynamic apnea, variable weight and free emersion are categories of what activity?

动态屏息、可变体重和自由浮现是什么活动的特征？

And this is a picture from emersion week emersion week is when the very first time students meet together that for 5 days to Penn.

这是一张开学周的照片开学周时，同学初次见面他们来宾州五天。