Laguna 69, a full day hike that will take you 4000+m above sea level, while enjoying one of the highest and pretty part of the Andes mountain range. If there is only time for one hike in Huaraz then this should be it. After my time here during the first day, I decided to stay 2 weeks longer in Huaraz alone to explore other parts of the mountain range.
If you are in Peru and you love hiking, skipping Huaraz would be a crime! ;)