This river has many rapids, so it's not suitable for canoeing.
The sound of the swift current could be heard from afar.
急流 is the general term for a fast-flowing torrent, while 早瀬 specifically names a swift, shallow stretch of a river and is common in place names.
急流 is the common, everyday word for a fast-flowing current, while 滝川 is a rarer, more literary term evoking a waterfall-like torrent.
急流 emphasizes the speed of a current, while 激流 emphasizes its violent, raging force.
清流 describes water that is clear, while 急流 describes water that is fast-moving; the two qualities are unrelated despite the shared 流 character.
river rafting; shooting the rapids
Compound of 急 (kyū, 'rapid') and 流 (ryū, 'flow, current'). The reading is on'yomi.