Luke 8.

31 „And they besought him that he would not command them to go out into the deep.”

At first it seems strange that the Legion of evil spirits first begged Jesus not command them to go out into the deep and than after Jesus casted those onto the pigs they made the pigs went down a step place so they died in the lake. So I looked this word up and its original meaning is a deep, bottomless pit(something negative). The same word is used in Rom10,7 where it is used as the place for the opposite of the heaven. So I think that we can assume that with this deep is not been a geographical deeper place meant but the hell which can be the deepest place.
Sometimes it seems that the devil is much cleverer and sees things clearer than us. We already can see in verse 28 that these evil spirits recognize Jesus as the son of God. And in this verse 31 we can see that they really do not want to go to hell. We human often forget who Jesus is and many people in the world do not acknowledge Jesus as the son of God. There are also many people who are not afraid of going to hell (There are some groups who worship the devil and whose aim is to enter the hell) and even want to go there. (This so called Satanism and there is also a “church” for them that’s really perverted)
So we are often blinded so that we do not see the good but want to do the evil and things that will hurt us.