Plans to tackle the second homes "crisis" in Wales are "vague" and "unambitious", a campaign group says.
Hundreds gathered at Llyn Celyn in Gwynedd on Saturday after the Welsh government announced plans to "inject fairness back into the housing system".
Gwynedd has the highest number of second homes at 5,098, which represents 20% of all second homes in Wales.
The Welsh government said it was "working at speed" for "sustainable solutions to what are complex issues".
Mabli Siriol, chairwoman of Welsh language campaign group Cymdeithas yr Iaith, addressed the crowd and called for "urgent action".
She called for measures including new taxes and legislation to bring in price caps on second homes, and "invest that money in our communities to bring houses back into public hands".
"What we've got from them is vague and unambitious promises - more consultation, more pilot projects - that will take years to make a difference, which is time we can't afford to waste," she said.
There were 24,873 second homes registered for council tax purposes in Wales in January 2021, according to official figures.
Officials say numbers of homes could be much higher depending on the exact definition of a second home.
Those looking to buy second homes or buy-to-let properties in Wales have to pay an extra 4% in land transaction tax (LTT) on top of the tax payable for their band.
New figures from the Welsh Revenue Authority show 44% of all homes sold in the Gwynedd constituency of Dwyfor Meirionnydd during 2020-21 were subject to the higher rate of LTT.
The area's member of the Senedd (MS), Mabon ap Gwynfor, told the Local Democracy Reporting Service: "These latest statistics show that the housing crisis is getting worse and that the Welsh government's decision to raise the LTT by 1% hasn't worked... we have to take much more ambitious steps."
Earlier this week the Welsh government said it would pick an area of Wales to pilot new policies aimed at "injecting fairness back into the housing system".
It said officials would also look at options to shut a tax "loophole" where some second home owners do not pay council tax.
The government has also said it will launch a Welsh Language Communities Housing Plan in the autumn.
A Welsh government spokesman said: "Fairness is at the heart of our plans, ensuring that everyone in Wales can have access to good quality, affordable housing.
"Within the first two months of forming a new government, we have set out plans to begin to address the impact of second and holiday home ownership in some communities and to protect the interests of Welsh language communities.
"We are working at speed to implement sustainable solutions to what are complex issues."