Between The Devil and The Deep Blue Sea
Entre la espada y la pared
We feel between the devil and the deep blue sea when we are in a very difficult position, between two great dangers. It refers to a very difficult decision to make.
There was a heavy plank fastened to one side of a ship in the 17th century. This plank was called the devil. It was used to support the cannons. There were times in which sailors had to go out to do some repairs to the devils. This was a very dangerous situation because the mariner could fall down any moment into the deep blue sea. If the ship got into a very tight area, the sailor could be easily smashed and die. That is why, this expression got an expanded meaning of being between two dangerous positions.