沿う
そう · sou · JLPT N3 · verb-godan
to follow
🧵 沿う sou sounds like sew: you sew along a seam, following its line
The kanji 沿 has the water radical 氵, so it first meant moving along the course of a river. It is used for following a road, a river, or someone's wishes: 川に沿って歩く = walk along the river.
沿 — water 氵 + 㕣 (marsh/valley) phonetic
沿 combines the water radical 氵 with 㕣, depicting a stream flowing through a small valley. Originally it meant to follow along the course of a river, and by extension came to mean 'to follow,' 'along,' or 'beside.' The 㕣 element also gives the sound.