海岸 (hǎi'àn) means "coast" or "shoreline," referring to the land along the edge of the sea. It commonly appears in compound words like 海岸警卫队 (coast guard).
我们沿着海岸走了一个下午。
Wǒmen yánzhe hǎi'àn zǒule yī gè xiàwǔ.
We walked along the coast for an entire afternoon.
这片海岸的风景非常漂亮。
Zhè piàn hǎi'àn de fēngjǐng fēicháng piàoliang.
The scenery along this coast is very beautiful.
海岸警卫队派出了船只去搜索。
Hǎi'àn jǐngwèiduì pàichūle chuánzhī qù sōusuǒ.
The coast guard dispatched boats to conduct a search.