Our Illiniza Sur trip began with making arrangements with Vladimir in the town of Machachi below the Illinizas. We rented horses to carry the tents, water, and heavy supplies up, though you could obviously do this yourself and use water available at the hut. He owns a large hostel where you could also spend the night indoors, get a hot meal and hot shower. We opted for absolute certainty of the cleanliness of our water and it was successful. Horses cost 12.00 US each way. We camped out on the sand next to the refugio, which continues to be a disgusting mold ridden, undiagnosed disease. We did, however, cook in the huts without problem. You will have to pay a 5 dollar park entrance fee to the "caretaker" of the park who shows up at the Virgen drop off in a green pick-up with a ledger. If you're lucky you'll miss him. The hut is also 5 dollars per night, per person for cooking and I believe 10 for sleeping.
A quick acclimitization hike on Illiniza Norte involved some scrambling, but was mostly a walk-up. There was a little bit of snow, during which having a mountaineering axe is advantageous, but not life-or-death necessary. Crampons were not needed. A helmet is recommended due to the potential for loose falling rock.
Now, for Illiniza Sur. We left at 4 a.m. and summitted around 7 a.m. We moved quickly. The route requires leaving the hut and following the "usual" trail up the hill. You will hike parallel to the mountain through the rock fall and under more potential rock fall. The glacier begins on one or two narrow ramps on the further "right corner", which require some mixed climbing for about 20 feet at worst. If you choose not to enter the glacier here, you will have to go down behind the mountain further and lose elevation for an easier walk-up onto the glacier. You can pick based on the conditions, which have been changing frequently. We stayed high. Once upon the glacier, the route finding is easy. One tends to stay right and begins with a moderately steep walk-up to the first flat ledge with a crevasse on the back side. From this point there were 2 options on our trip. One was a steep ramp going to the left of the crevasse. The second was a steep ramp and mixed climb requiring a snow fluke belay. The climbing is steep, but short and not overly technical during this 60-70 foot section. You can get really stoked on that side. You can also hang more to the left and avoid the rock, making it an approximately 60 degree pitch of just ice/snow.
After completing that pitch, you have the final approach which is more steep walking up the ramp and very direct. The summit is small compared to other mountains in Ecuador with glaciers. On our morning we had amazing view of the five highest peaks in Ecuador. The descent is quick and follows the same route up. On the very bottom section, a rappell is possible by anchoring off a boulder thus avoiding some of the scrambling and mixed down-climbing. Half of our team down-climbed (on belay) and the other half rappelled. You will want to get down quickly once the sun is up to avoid the very serious risk of rock fall during the parallel traverse back to the main trail. It can also get foggy and cloudy. Taking a GPS and putting in way points would be highly advantageous for the descent. The night previous two climbers got lost on Sur, though did finally safely return in the middle of the night. Temperatures were in the teens, with a gusty wind around 4:30 a.m. making crampon adjusting slightly challenging.