As I am looking for the towers that unlock the door underwater at route 11 I can't seem to find one of the towers that unlocks the door. I also found one tower by aquamarine cave but I am not to sure if it is even relevant and if not what is its purpose. Also, I can't seem to access it since when I move towards the tower it asks me if I want to swim along the side, saying yes or no does not do anything after.