A wonderful place to visit, it's currently easier to access by vehicle (to a certain extent) and with parking. However, if you're someone who enjoys climbing mountains over 4,000 meters from the bottom, I'm sure you'll love the challenge.
Don't forget that these are mountains, and weather changes can happen at unexpected times, so it's best to be prepared for anything, bringing hydration and food necessary for the effort and the weather.
In the craters, you'll find two bodies of fresh water that form the Laguna del Sol and Laguna de la Luna. In the 1990s, you could dive at altitude in the icy waters. Visibility is very low, so it was done with instruments and good orientation, a dry suit, or a wetsuit for icy waters. Currently, only research personnel can do so with a special permit, as it is an ecological and archaeological reserve.
Admission is fee-based, and on weekends, it's very crowded, so be patient and always respect the place. Leave it better than you found it, and enjoy!
You can also get there by gravel bike or mountain bike, but achieving this requires good training due to the incline and altitude.
Always remember: Respect the Mountain.