Well this isn't really a secret, but few people are familiar with this trail down to the Chinese Pioneer bridge. You can park anywhere along Champions road, hop onto the canal trail, and get to gz. Once at GZ use your geosense to find the cache. Your feet do not need to leave the trail to find the cache, but you might want to get on your knees. After finding this cache, head on down the steep windy trail to the river and the bridge. There is some fun on the other side as well.