The Welsh mountain, which is in Snowdonia, one of the country's top tourist destinations, is popular in part because it can be walked on foot without specialist climbing gear.
Visit Snowdonia, which manages the national park for the Welsh government, told people to keep away from busy places on the weekend.
They said in a statement: "Ahead of another fine weekend expected here in Snowdonia, we ask you all to help us keep everyone safe by adhering to the Welsh Government’s Covid-19 guidelines, and having a backup plan if you arrive somewhere which is clearly too busy."
But footage taken on Saturday appears to show dozens of people bunched up together on the path leading to the mountain's summit.
Some people reacted to the scenes on Snowdon with frustration and worried that climbers could be spreading coronavirus.
On seeing the video, one person said: "Do people really not understand what is happening right now? Staggering stupidity, which is eventually going to lead to another total lockdown."
Another added: "Glad to see them social distancing".
A spokesperson for Snowdonia National Park Authority told the Standard that this season has been the busiest on record for the park and queueing for the summit has become normal.
"It's been a good boost for tourism businesses after huge losses for them in lockdown, and the majority of visitors have been respectful of each other and of the area, but the vast numbers do raise a number of challenges for us in looking after the National Park," they added in a statement.
The spokesperson continued: "We're urging hikers to think about how busy the area they're visiting are likely to be when planning their trip with Covid being on the rise again and to make sure they are adhering their own local as well as national Welsh restrictions and guidance.
They added that the "amount of litter, illegal camping and antisocial behaviour... this summer has been unprecedented" and urged visitors to clean up after themselves to avoid the "disheartening" scenes.
Scientists think coronavirus is much less likely to spread outdoors than indoors, although there is still some risk, especially if people are close to each other.
Deputy Chief Medical Officer Jonathan Van-Tam said in May that "it is absolutely categorically clear that outdoor spaces with higher degrees of ventilation are less problematic environments for transmission than indoor spaces."
Coronavirus infections continue to rise rapidly in the UK, with stricter restrictions recently imposed, including a 10pm curfew for pubs and restaurants.
In Wales, Scotland and Northern Ireland restrictions are even more severe than in England, with a ban on people mixing in the homes of people outside their extended household.
Cardiff, Swansea and Llanelli have all been placed under local lockdown this weekend after a rapid rise in cases.
From 6pm on Sunday people living in Cardiff and Swansea will not be able to travel in or out without a reasonable excuse, or meet indoors with anyone they do not live with.
The same rules applied to the Carmarthenshire town of Llanelli from 6pm on Saturday after a spike in cases there.