I suppose it could be a lesson in night navigation?

我想这或许可以是一次夜间的导航课程？

youdao

They were also used in harbor channels for navigation at night and in fog.

港口和海峡也会用于夜晚和雾天的导航。

youdao

They were also used in harbor channels for navigation at night and in fog.

港口和海峡也会用于夜晚和雾天的导航。

youdao