This is the standard route and the most common by a wide margin.
Start at Lago Limpiopungo. For directions see Getting There in the mountain description.
From the parking lot travel around the right side of the lake. There is a narrow trail to follow. Stay on the trail until you are on the opposite side of the lake. You are looking for a large meadow with a small streamlet running through it. Steeply asending a hill on the left is an obvious trail. That is the start of the route.
Leave the meadow and start up the trail. You will be following this trail for some time. As you get to the flats higher in the valley the trail becomes indistinct. No worries, just keep hiking up toward the mountain.
Eventually you will be in a broad valley between the Sur and Central peaks. You need to gain the grassy ridge to your right. Cross the meadow (potentially soft and swampy, stick to any high ground) and climb the grassy ridge. Their are a some use trails in the area.
On the ridgetop follow the trail towards Rumiñahui Central. Enjoy the trail while it lasts. Your objective is to traverse over to Rumiñahui Norte. You can follow the trail part of the way. Do not go to high too fast. It is easy to get sucked into some of the gullies and climb up to the ridge, but don't do that. You need to traverse under a number of dikes or ribs to get to almost the last gully on this side of the mountain.
In this gully which is reddish near the top, you will ascend to the crater rim. Only 85 vertical meters remain. At the rim, ascend slightly to the left before dropping down and then back up. You should be seeing something of a path and some cairns as well. Follow the path to the summit. Watch your footing. This is not a route to do when things are wet. The mud and sand becomes rather slippery over some fairly long drops.
This is a hike followed by a scramble. All you really need is your standard dayhiking gear.
If you have information about this route that doesn't pertain to any of the other sections, please add it here.