Roller skating has plummeted in popularity throughout much of the United States. Denver is one of the cities that has been hit by this.
Skate City has five roller skating rinks throughout Colorado. Unfortunately they do not have one in Denver, but they do have one in nearby Aurora.
The Colorado Tennis Association has a court finder on their website and information on juniors, adults and seniors.
According to the Colorado Tennis Association there are 74 tennis courts within Denver of varying public access levels.
Perhaps not surprisingly, hiking in Denver is extremely popular. It is not too difficult to get out of Denver if you're itching for the great outdoors. Some excellent hiking trails are available and often just for the cost of parking. With an estimated 572 trails from Trails.com in the Denver Area, you're bound to find one that fits your experience level and time.