About 10 minutes outside of Idaho Falls there's a hole in the ground that happens to be 17 miles long! The first real date I took my wife on was to 17 mile cave and obviously it worked. We brought two headlamps and a speaker down into the cave and a couple cans of spray paint because the walls are covered in graffiti. We went down in until we found a spot that opens up and I set the speaker down and connected my phone. Make sure you have your songs downloaded cause there's no service in the cave. We listened to a couple of my favorite songs and then spray painted our initials on the ground cause it was one of the only places that was clear. Honestly one of the best dates I've been on and it was better than your typical soda vine and a movie.