sea moat

例句：

1. 1. The sea moat is a crucial defense against intruders.
   海堤是抵御入侵者的关键防御。
2. 2. The castle has an impressive sea moat that stretches for miles.
   这座城堡有一条令人印象深刻的海堤，绵延数英里。
3. 3.The ancient city was surrounded by a sea moat to protect it from invaders.
   这个古老的城市被一条海堤包围，以保护它免受侵略者的侵害。