by sea

by means of a ship or ships

乘船

other army units were sent by sea.

其他部队通过海路运送。

go to sea

set out on a voyage

出海航行

on the sea

situated on the coast

在岸边

put (out) to sea

leave land on a voyage

离岸出海

at sea

On the sea, especially on a sea voyage.

海上的，尤指海上航行

In a state of confusion or perplexity; at a loss.

茫然，不知所措：处于混乱的或困惑的状态；不知所措