Coastal Waters
Coast
noun, の adjective
The run alongside sea is the sea that runs alongside the land, making it the coastal waters aka the coast.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
沿海部での生活について、月一でコラムを書いてみませんか。
Would you like to write a monthly column about life in coastal areas?