Paron Grande is the main prominent mountain laying at the very end of the Paron Glacier. The mountain is covered with heavy snowfall, got snow cornices and ice mushrooms. Also global warming of the last decade made the access to the summit area the more and more difficult. To summit the mountain you will have to negociate several crevasses and two big berschrunds. The easiest route to the summit is rated in Johnson's and Sharman's book at AD but these days is significantly more difficult with objective avalanche risk and difficult route finding.
It is good to acclimatise but not really easier than Artensoraju, it is just a shorter climb.
From Lima take a bus (several service per day, the best companies being Cruero del Sur and Moviltours) for Huaraz. The journey is seven hours long and costs 10 to 20 USD according to the service and company chosen.
Huaraz is 3,091m and got all the facility a climber needs. From Huaraz take a local mini-bus to Caraz for about 2 USD. There by taxi you can get to the "Laguna Paron" on an unpaved road for a price of 20 USD. You can arrange to the picked-up but for this the driver will request the half of the money front. I suggest not to book any service, on the way book you will take the taxi of one of the climber, trekker or simple tourist frequently there for the day.
The taxi will leave you at the end of the road, near the hydro-electric plant main building. From there 1.5-2 hours trekking and you will get to the low camp, called also base camp. It's closed to the river, at about 4,300m adequate to acclimatise. From the base camp there are 2 hours hiking uphill before getting to the moraine camp located at 4,800m. This camps is common to climb by the normal route Caraz, Paron Grande, Piramide de Garcilaso and Artensoraju. From the moraine camp descend the morain to get on the glacier and then hike uphill to a safe spot in the middle of the glacier at the base of Artensoraju at about 5,000m. From this location the summit of Paron Grande is about 7 hours.
The moraine camp is the last place with liquid water (small stream near-by).
There is no fee enforced in the area but technically you need to pay the fee for the Cordillera Blanca (about 20 USD). If you do not climb other mountains you can escape this but if you climb other mountains like Alpamayo, Huascaran, Toclaraju you will have to. I have nothing against paying fee for conservation, the issue is just the money paid do not go to the parks.
As you are in a park common rules apply.
Camping is allowed and indeed necessary (see section above).
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When to go
The best season to climb is from June till late July. In August wind starts to be a nuisance and in September the rainy season starts.