The government is putting €30m into a plan to develop new islands in the Markermeer lake, north of Amsterdam.
The aim of the project is to create additional natural resources in the lake, improving conditions for wildlife and the quality of the water.
The islands will be made by dredging up sludge from the bottom of the lake, which will also make the water clearer.
The plan, drawn up by the Dutch national heritage body Natuurmonumenten, is supported by both Noord-Holland and Flevoland provincial councils.
Natuurmonumenten puts the total cost at around €75m. Last year, the Postcode Lottery donated €15m.
The Markermeer used to be part of the Zuiderzee, a saltwater inlet which was closed off from the North Sea when the Afsluitdijk was built across it in 1932.