Sea
Ocean
A tsunami is coming, so you point your gun out the window at it. "You better turn back, sea, or I'll shoot!"
かい
うみ
None
The sea decides it doesn't want to die today, so it turns its tsunami around and goes the other way. You hop in your kayak (かい) and chase after it with your gun, to make sure it actually returns to the sea and doesn't just drown someone else.