Upper raft - Kami raft

...Depending on the size of the raft, about 2-3 people would ride on it, and each raft was called Sakinori (also called Henori or Hananori), Nakanori, and Atonori (also called Tomonori) from the front, with the Sakinori handled by an experienced person. At the relay point where the river widens, the upstream raft was called the upper raft and the downstream raft was called the lower raft, and the lower rafts would often be in two to four columns. There are many difficult spots along the river, with rapids and rock faces, and rafters often lose their lives there, and some rocks are named after those rafters.

*Some of the terminology explanations that mention "Kami-raft" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…いかだの大きさにもよるが，およそ2～3人乗りで，それぞれ前からサキノリ(あるいはヘノリ，ハナノリともいう)，ナカノリ，アトノリ(トモノリともいう)といい，サキノリは熟練者が当たった。川幅が広くなる中継地点を境に，上流を上いかだ，下流を下いかだともいい，下いかだは2～4列縦隊にもやう。河流の途中には，瀬や岩壁の難所があるところが多く，そこで命を落とすいかだ師も間々あり，そのいかだ師の名をつけた岩もある。…

※「上いかだ」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報