There's no boardwalk, no waves, no surfers and almost no sand, but the tiny riverfront stretch down the hill from Commons Park is a peaceful way to grab a little serenity in the midst of a busy city. Close your eyes and listen to the Platte River as it trickles (or rushes after a rainfall) over the rocks and concrete at the base of the pedestrian bridge. Sit back and check out the dog lovers as they let their pooches swim around in the muck, or the tai chi types while they show off their moves. You can even chill a couple cans of your favorite beverage in the water. If you don't mind the grime, pick up a piece of driftwood, a little shell or a rock and skip it across to the other side. Oh, and don't forget the sunblock; after all, Denver beaches are a mile closer to the sun.