Known as Guchhu Pani by the locals, Robber's Cave is situated about eight kilometres from Dehradun. To reach the spot, you'll have to trek for about a kilometre and then you'll be able to witness the beautiful, natural river flowing from the middle of a cave.
Just in case, you are willing to trek for about half a kilometre more, you'll also be able to spot a waterfall.
The entry fee for the same is INR 25.