Underwater Practice

It was a fun class today, but I was a little frustrated. We practice underwater swimming, which helps us feeling more familiar with water and the effect brought by our body movement against water. I did not do a lot of this kind of practice before and I am not good at it. I don't know when my breath exhausts and have to come up and breath very well, and my body movement is not agile enough to getting through the circle underwater without touching the circle at the end. Some people who do not swim very well can do those practices easily. I think they have many experience to play in the water, but just need to learn standard swimming. I go to swimming pool only for swimming, but never have fun like this. This is the difference.
Later, I practice the figure-8 sculling a little bit.