The door to hell
Located in Turkmenistan, this is a natural gas crater. The purpose to create this is to set on fire to stop its dangerous spread. It is quite surprising that it has been burning since 1971. Visitors who are interested to visit this place go there and form camp around this crater and it seems like they have been near a door to hell.
These are all pretty freaky places which only a brave person can visit who likes to make adventures.