The natural pools of Semuc Champey are one of the most popular places to visit in Verapaz, Guatemala. To get there from Cobán, you need to take a shared minibus until Lanquín or a direct minibus to Semuc. From Lanquín, you can easily find transportation on the street or via your hotel which will surely offer to arrange a trip for only 20 Quetzals or so for only transportation or around 120-160 Queztals for a full tour including visits to the caves and tubing.
The entrance fee to the park is 50 Queztals (a bit over $5.00) and the park is open until 4:00pm. If you go with a tour, you probably won't have too much time to enjoy the pools, but if you go on your own you can spend all day enjoying the amazing lookout post and splashing around in the pools.