A private company is to take over the running of the Plas Menai National Outdoor Centre.
Sport Wales will continue to own the watersports facility, but it will be operated by Parkwood Leisure.
Plaid Cymru politicians expressed concerns that the decision had gone ahead "despite collective opposition" from the local community and unions.
The Welsh government said the centre will still be run on a not-for-profit basis.
Officials in the PCS union had earlier expressed concerns over the potential for a private operator running the site, which is located between Bangor and Caernarfon.
National officer Darren Williams had said workers did not want their jobs to be moved to a provider that could be putting profit ahead of promises to the public.
Plas Menai offers courses and training in dinghy sailing, windsurfing, powerboating, cruising and kayaking, as well as a swimming pool and fitness room.
The decision followed a procurement process by Sport Wales to find a partner for the site.
"Parkwood brings extensive knowledge and experience of the outdoor and leisure sector together with innovative delivery proposals," Welsh government deputy minister for sport Dawn Bowden said.
"This approach will bring in sector experience and expertise to grow the business as a year-round sporting destination, which will enable the long-term growth and development of Plas Menai."
Staff at the centre will have their terms and conditions protected, she added, and Plas Menai will retain its status as the National Outdoor Centre.
Plaid Cymru MP for Arfon Hywel Williams said he was "disappointed that a decision has been made to transfer the day to day running of Plas Menai to an arm's length, private enterprise – despite collective opposition to such a move from within the local community and the unions".
He said it was the "wrong decision as this type of business model almost always leads to less accountability, variable service standards and workers' rights".
His party colleague, MS for Arfon Sian Gwenllian, added: "I hope that this is not the beginning of a slippery slide towards the privatisation of leisure facilities by Sport Wales which is funded by the Welsh government.
"We need to know what Parkwood Leisure's short and long-term plans are for the centre and they should fully engage with local stakeholders about their ideas for development."
Gwadu preifateiddio Plas Menai ger Caernarfon
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