C609 Three-line strategy(part i)

Long Tianci had studied the map for a long time, but he couldn't figure out what exactly this place was marked. Just looking at the map, this point should be in the sea, could it be that the thing marked on the map is below the sea?

Honestly speaking, ever since Long Tianci first came in contact with this sea map three years ago, he felt that this sea map was extremely strange