The Polar Bear 5k is a fun course at the Horsetooth Reservoir South Bay Campground. Rolling hills, nice dogs on leashes allowed, do it's at the finish line (as well as other snacks), the shirts are always cute, plenty of parking. I've done this race for 5 or 6 years, it is managed very well, and it's always fun. I live near by, so am able to "be green" and walk the mile to the race start. Highly recommend. I have never done The Plunge, but it is a benefit to the Dive team rescue. Alway fun to watch and cheer people on who are doing it. Soup is available afterwards for those who do the pkunge🏃‍♀️