I'm thinking of dumping the body in the mountains
Thats horrible! Why would you dump a body in the mountains instead of telling the police where it is!?
I don't see why anybody would care.
Dumping a body into any environment is against the law and you will end up in jail for this. You need to go straight to the police and confess why you are in possession of a body in the first place.
Nope I'm going to keep it here!
That body is someone's loved one, family or friend. By keeping the body hidden from them you're not allowing them to have closure by being able to bury it. You're also violating laws of decency by treating the body as an object you own.