Hello, my boyfriend and I are planning to road trip from Indiana to Colorado for a vacation. We have never been to Colorado before, so I’m looking for any suggestions about visiting! We don’t really care for the big cities, but want to explore the nature side of Colorado. We are planning for the end of September. What is a must see? The things we want to do during our visit is a natural spring, zip lining, kayaking/canoeing, swimming, and hiking the mountains. We plan to be there for a week. Thanks!

A few obvious choices: Rocky Mountain national Park, Mesa Verde National Park, the train ride between Durango and Silverton.

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By natural spring I assume you mean hot springs?

https://www.colorado.com/articles/29...gs-quick-guide

For kayaking -

https://www.uncovercolorado.com/kaya...-rivers-lakes/

For ziplining -

https://theknow.denverpost.com/2017/...lorado/149715/

For swimming -

https://303magazine.com/2017/05/best...swim-colorado/

For hiking - well, just about anywhere, but here are a few suggestions:

https://www.alltrails.com/us/colorado

Are you driving to Colorado or flying? If flying, where to?

A drive through the San Juan Forest on Rt 550 in southwestern Colorado is gorgeous . Also Great Sand Dunes National Park just south of Colorado Springs is pretty cool. Garden of the Gods is also near there. Pretty much cant go wrong with any hikes in the western half of the state.

Just to clarify, Garden of the Gods is in Colorado Springs. Great Sand Dunes is near Alamosa some 2.5 - 3.5 hours south of Colorado Springs, depending on your route.

You can avoid driving across a couple of what some people consider "flyover states" like Iowa and Nebraska. Instead of flying, I like to take the Amtrak California Zephyr at least one way. One of my favorite stops on the Zephyr is at Glenwood Springs. There is a great hiking/bike trail to the east through the Glenwood Canyon. Also in Glenwood Springs is the world's largest hot spring fed swimming pool and a chairlift up to a cavern.
There is a great bus service from Glenwood Springs to Aspen (about 40 miles).
Currently, Amtrak is running the Zephyr three days per week out of Chicago but I hope that it will get back to a daily train sometime this summer. Coach seats are at 50% capacity with everyone sitting in a window seat. The Roomettes are a good choice where you can close the door when you want to. The sleeping car attendant will deliver food to your Roomette if you don't want to dine in the dining car.

Is it a week from home and back to home or a week total IN Colorado? Depending on where in Indiana, the drive would take at least a day and a half each direction without sightseeing detours or stops.

And if you are going to get on a public carrier why not just fly. The tickets are ridiculously cheap and it takes 3 hours to get to Denver.