The cache is not at the posted coordinates, although it is a good place to park. First you will need to complete the Adventure Lab next door, and then drive or hike to the posted coordinates for a short stroll to the bonus. Each completed Adventure Lab stop will reveal a digit which corresponds to a letter in the puzzle. You can confirm your final coordinates with the checker provided. Solve the nearby Bergen Park Adventure Lab for actual Geocache coordinates. Final is located at N39 40.ABC W105 21.DEF Good luck, and Happy Hunting!
Learn more about Advenure Labs here