You are looking for an ammo can in the East River Flats. Inside you will find a wide variety of puzzles. Feel free to trade puzzles of your own with those in the cache.
There is one unique puzzle in the cache that is not for trade. This puzzle contains the log book and must be completed to sign it. You will understand when you get there. Due to the nature of this as a puzzle, YOUR NAME MUST BE IN THE LOG BOOK TO CLAIM THE SMILEY. The required puzzle could take anywhere from 2 minutes to half an hour. This puzzle does require patience and a steady hand.
There is close parking located at the waypoint below, but it is closed during the winter. As the snow begins to fly, it might be best to park across the street above the cache. The terrain will still be the same rating, which pertains to the last 50 feet. It is a 1 until then. From below, once you get the the bench, just follow the angled logs up and to the right for the easiest access. From above, just drop down the wide, fenceless gap. Enjoy!
When I placed the cache, I forgot to include a writing utensil. All I had on me was a pen. Since it is cold and it might freeze, remember the logging requirement and please bring a pen or pencil. If someone would be so kind as to throw in a pencil or two, that would stellar. Thanks.