We visited the Millpu Canyon on a day trip from Ayacucho with the travel agency Huancaraylla Tours. We were very satisfied with the experience and would recommend going on a tour rather than independently, because it is easier that way and the tour allows more than enough time at the site to make the most of it.
It is a very long drive (3 and a half hours each way) on an extremely windy road to get to Millpu. If you get motion sickness I strongly recommend that you take some medication, because almost no part of the road is straight.
Once at Millpu the guide gave us 3 hours and let us walk at our own pace, we did not have to stick to the group. For people who are used to hiking this is an easy hike, it takes around 15 minutes to arrive at the first pools and approximately an hour to get to the top of the canyon. There is a turn off down hill to get to the pools. It is no longer allowed to swim in them thankfully, as the combination of constant movement of the water (lifting those minerals that give the water its colour) and dirty bodies meant that the water was loosing its wonderful colour and fungus was spreading.
There are many amazing viewpoints along the well established path from where you can see the pools from above, what a sight! The path goes uphill, with some stairs sections, but it is never really that steep.
We visited in mid October at the beginning of the rainy season, but had a beautiful sunny day and the pools were a vibrant turquoise/emerald colour. Apparently when you come in the dry season (from May to September) the pools have a more turquoise colour and when you come in the rainy season (from October to April) the pools get a gradually more green colour. In January, February and March the travel agencies do not offer tours to Millpu.
We ended the day eating a truly delicious trout at one of the restaurants at the trailhead.
Millpu is a completely unique sight, so I would definitely recommend a visit there, however, I was most shocked to find out that many foreign tourists that come to Ayacucho only come for a single day to visit Millpu and then carry on their journey to Lima or Cusco without visiting any other sights. What a waste of opportunity given that Ayacucho is one of Peru most attractive and pleasant towns offering a marvelous variety of natural, historic and cultural sights, as well as fantastic restaurants and accommodation. So my advice would be to stay at least 3 days in Ayacucho.
I would not recommend visiting Millpu during national holidays, whether it be for Easter, Independence day or any long weekends, because the sight literally gets jam packed with national tourists. When we visited on a week day in October there was barely anyone there, which was obviously very enjoyable.
There is a S/5 soles entrance fee to visit Millpu, which goes to the community.