Underwater Railroad

I was walking by myself in what seemed like a military base in a desert type climate. Sandy roads, concrete buildings, etc. All of the sudden, a group of guys asked me to play disc (frisbee) golf with them. I agreed and they asked me to go ahead and throw first shot. I remembered that the hole was 6,437 feet slightly uphill and to the right (in real life, this would be an impossibly long hole. Pretty much the length of a full 18 hole course). I threw a forehand shot (with my favorite disc in real life), only I was shocked to notice almost immediately that I had thrown it upside down, causing it to go the opposite direction that I intended. It went straight into a canal/river of sorts off to the left. I ran after it in hopes to retrieve it, but the water was very treacherous. It felt as though if I ended up falling in, I would certainly die. The water was that intense. So I did not jump in after it. The disc started to get close and I reached for it but it was just out of reach. It continued to quickly float back behind us and I ran after it to see if it would get a bit closer. It went through a short tunnel and I waited for it on the other side. Once I caught a glimpse of it I noticed something in the water emerge into sight. It appeared at first as if a torpedo was being fired. Upon closer look it was more like a submarine. But it was on a type of underwater railroad system. When I looked closer, it was as if I was now under the water, able to view everything more clearly. The underwater submarine railroad system was very impressive. I had the feelings of, "wow this whole system is just right here and no one had any idea!" It felt powerful.