Going to see the monarch butterflies at the sanctuary was an amazing experience. We were 2 adults hiking up and our 18 month old baby in a baby rucksack. We were told by locals as well as the guides that it is a difficult hike and to consider going horseback. We are an active, athletic couple that likes hiking but living at sea level in Playa del Carmen, Mexico, we don't get to do it very often. Even so, the hike was manageable (even with a baby on the back), the hardest thing being the adjustment of hiking at a higher altitude. We went up with 1 guide and were followed by 2 guides with horses for the first 20 minutes, constantly asking if we were sure we didn't want to go up by horse- a little bit too pushy for my liking. Finally they left us alone and we continued up. We paid the $100 MX sanctuary entrance fee. Experiencing the butterflies in their natural habitat was well worth the hour trek up to 3000m, and the hour stay we had with them. There were millions, so many that you can hear loudly the flapping of their wings. The way down was obviously much faster, a quick 30 minutes. Going by foot, we were only required to pay $200 MX to the guide and this was made clear to us from the beginning, when we were also offered to go by horse for $200 MX each. Our only complaint was that the guide explained nothing. We could've just as easily walked up using a map of the trails (which doesn't yet exist). Still, worth the trip as it's one of the few places to witness this amazing migration.