The Montenvers train is a rack and pinion railway (funicular) that departs from Chamonix and takes you to a panoramic site of the Mer de Glace Glacier.  The train ride is about 30 minutes long and typically departs every half hour, however be sure to check the website for specifics on departure times and annual closures.
Eliana, Lucas and Henry riding the Montenvers Train February 2017
The train ride up the mountain is scenic and enjoyable, but nothing compared to the views once you reach the top.
After departing the train at the Montenvers Site
Riding the Montenvers Train
Once you reach the top, you are greeted with a touristy store selling postcards and warm clothes (people must come under-dressed) and a casual restaurant.  You will also find signs that will lead you to the gondola that will take you partially down to the Ice Cave.  The gondola is essentially a box with full glass windows that hangs from a cable and takes you down a steep descent (or ascent on the way back) quickly.
Boarding the Montenvers gondola

Inside the gondola, heading down to the ice cave
 After departing the gondola, you still have 480 steps to take before reaching the ice cave.  The steps are a set of sturdy metal stairs with a handrail, but be prepared for the walk (or better yet the walk back up!)
About to walk down the 480 steps after getting off the gondola (gondola shown above us in the photo)
Getting closer...
Eliana described the ice cave as Elsa's (from Disney) Cave:
Inside the ice cave
Just after the entering into the ice cave
About to exit the ice cave with Aunt Ren
After touring the ice cave, we made our way back up the 480 steps and then took the gondola back up to the top.  Once at the top, we ate a well deserved meal at the restaurant with incredible views of the Mer de Glace glacier and the mountains.
You have an option of sitting inside the restaurant or outside on the veranda - make sure to have a reservation!

On a separate trip with Grandma and Pop -  September 2017

Visiting the Montenvers Site with Grandma and Pop - we skipped the gondola and ice cave this trip

For a link to all of our photos from this outing click here.

The town of Chamonix, where the Montenvers train departs, is also very cute and offers other outings and hikes as well, such as this hike to a mountain restaurant named "La Floria":