Japanese traditional training in the sea

I'm teaching "long distance group swimming in the sea" there days for high school students. They swim 4km or 2hrs distance swim by constructing formation. This would be an important & wonderful experience for students in their life. There is something nice rather just swim a long distance.
I hope students would get one of their treasure for their life, and I also have an good experience through teaching them. It's very thanks for each other.
Then, it remains two days for this camp...