Usage of を when meaning along/through


> ＫＵＲＯＳＨＩＯのロボットは長さが５ｍぐらいで、 **深い海の中を** 時速８ｋｍ以上で動くことができます。  
>  The KUROSHIO robot is around 5m long and can move through the deep sea at
> speeds in excess of 8km per hour.

I was wondering if 中 was necessary in this sentence. If we omit it, would it
be interpreted as the robot moving **on** the surface of the sea? I would have
assumed that the addition of 深い would make the intention clear without needing
中.




It is understandable without 中, but then it could also interpreted as _on_ the
sea. So it is better to explicitly say 深い海の中.

And especially since it is the sea is deep (深い), maybe the author wanted to
express that the robot can literally move pretty fast through it.




It is understandable without 中, but then it could also interpreted as _on_ the
sea. So it is better to explicitly say 深い海の中.

And especially since it is the sea is deep (深い), maybe the author wanted to
express that the robot can literally move pretty fast through it.

