Big Thunder Mountain Railroad is a fun and somewhat mild mine train roller coaster located in Frontierland at the Magic Kingdom. It zips in and out through the tunnels of the mountain. The rocks, moutains, bones and everything looks so cool.
Check out a short video of the entire ride below. There are a few dark places in the attraction that didn't show up good so you'll just have to go and see it for yourself. Watch in the video at about 4:02 as it looks as if you are about to run right smack into the side of the mountain and then it dips down.
The ride itself is a little over 3 short minutes. I'm beginning to see a trend in these long lines when it comes to short rides. Fastpass is available for this attraction which I do recommend. We did the mistake of getting on without the fastpass and we waited a little over an hour and it was the busier time of day in the afternoon.
My recommendation is to definitely not miss this one. I am not a big roller coaster fan but this one as I said above is mild compared to others and the scenery is great. Not to mention how cool the ride is with the wind blowing on you as you whip around the tracks in the hot summer sun.