Before moving to Colorado I never knew how much there was to do here. I knew there would be great hiking and skiing, but never in my life would I have imagined trying so many unique outdoorsy activities upon getting here.
1. Climbing (Telluride Via Ferrata)
This one is arguably kind of far from Denver, but so worth it! This was my first time doing a via ferrata and it was the most terrifying and adrenaline-filled activity I've ever done. You find yourself suspended around ~500ft in the air connected with just some carabiners and a rope to this massive rock wall in Telluride, with the sun beating down on you. The views are unmatched and it feels like you've been transported to another world. I'll preface with the fact that i'm not a climber by any means, but I did go with a friend who considers himself advanced/expert, which I recommend. Colorado is all about the thrills, and i'd say this is about as thrilling as it gets. This is free as long as you have your own gear, you just hike up the trail, clip in, and start going from right to left facing the mountain. There's a hiking trail down once you've scaled the 2+ miles of the wall.
2. Hiking or Driving to the top of a "14er" Mountain
This is the classic thing to do near Denver Colorado when you're visiting. Colorado is known for its incredibly accessible hiking trails, but one thing many Coloradans take pride in is how many "14ers" they've conquered. 14ers are trails that go above 14,000ft in elevation. There are two 14er mountains that you can drive, Pikes Peak and Mt. Evans, but check their local sites for closures as Mt Evans was most of 2020. They are both located within 2 hours driving distance of Denver. Altitude sickness is no joke though, so take some ibuprofen a few hours before the hike and hydrate A LOT! The sun is 50% stronger on these hikes since you're so much closer to it.
Carefully choose which one you decide to do as some can be quite dangerous since the hikes turn from trail to rock scramble once you approach the summit. A friend of mine did a 14er with a less-experienced hiker and she ended up falling down the side and having to be rescued, so choose beginner level ones unless you're sure you can do it! Also, wear a climbing helmet to protect yourself from rockfall, especially on crowded trails.
3. ATVing
This is absolutely worth trying if you want to splurge on a fun activity. Sometimes hiking can get exhausting and you just want to experience the views without all the effort. ATVing was such a fun and different way to explore the mountains - you go pretty fast and aren't limited by your physical capabilities. I tried this out in Vail at Nova Guides.
4. Swimming (or Skinny Dipping) in an Alpine Lake
Alpine lakes are bodies of water positioned somewhere above 10,000 ft in elevation, and they're usually very cold and above the tree line. While the water can be very cold, it is often clearer than lower altitude lakes. I definitely recommend this in the summer, not the fall like when I tried. I also did this while solo hiking, which I wouldn't recommend unless you trust yourself as a swimmer. This is loveland pass lake, some others you could try near Denver would be Brainard lake, Lake Isabelle, Hanging Lake. If you don't mind a drive, I would recommend some of the prettier ones in Ouray if you're out further (e.g., Blue lakes, Alta Lakes, ice lake basin, etc.)
6. Whitewater Rafting
This one probably doesn't come as a surprise for Colorado either. You can find rapids for rafting just 20 minutes outside of Denver in the Clear Creek/Idaho Springs area. Levels of skill range from beginner to advanced, so be sure to read up on the classes/levels before signing up!
7. Skiing and Snowboarding
This one is obvious, but it's what Colorado is known for in the winter months, so it's definitely a must-try while you're here. Two of the popular passes are IKON and EPIC, try to use student discounts when you can since they can be quite expensive! Start out on the easy slopes and work your way up to the more advanced, I've met tons of people here who have torn ACLs from skiing here, so be careful and have fun! If you're a beginner I recommend going to Breckenridge or Vail / Beaver Creek. If you're intermediate I highly recommend Winter Park and Copper! My favorite resort is Aspen Snowmass, especially as an intermediate to advanced skier. If you like backcountry, checking out A-basin is probably for you!
8. Dispersed Camping
Many of us are familiar with making reservations for established campsites at National Parks, and that's most of what i've done in the past. However, there are lots of National Forests and BLM land for you to explore and connect with the wilderness! Dispersed camping is more "primal" as in there are no bathroom facilities, no fees/reservations, and you have a much more private place to enjoy the stars. It's often referred to as "car camping" as you just drive your car down a dirt road in a National Forest (non-private land) and pitch your tent next your car. The best thing about dispersed camping is more privacy and it's free!
9. Zip-lining
If you need adrenaline, but in a controlled environment, I definitely recommend trying out zip-lining! I did this over the Royal Gorge in Southern Colorado, but they also have some options outside of Manitou Springs like Cave of the Winds.
10. Visit the Paint Mines
This area is not dog-friendly, but it's super colorful and beautiful! If you're looking for something to do on your way to check out Colorado Springs and Garden of the Gods for the day, then stop here on your way back!
11. Natural Hot Springs
When I used to think of hot springs, i'd immediately think of my trip to Iceland since that's what they're known for. I have no idea that Colorado has some of their very own scattered all throughout the state. While winter is the more ideal season, it does get chilly at night in the mountains to justify trying them out in the summer. Nothing's more relaxing than that after a long day of hiking. The snowy one below is Strawberry Hot Springs; I prefer it when it's cold out after a long day of skiing, but you can also go during the summertime! Make sure you make reservations on their website in advance. The other one pictured on the left is Box Canyon hot springs in Ouray and this is for guests of the hotel only.