The $4 million project, by the company Beladon, will have 40 cows on a 1200 sq.m floating platform, producing 1000L of milk a day to be pasteurised and made into yogurt in a dairy on the floor below.
The building will be concrete, relatively light and buoyant, with galvanised steel frames and a membrane floor that lets bovine urine soak through. A machine will collect dry dung, another will top up food stations.
The cows will wander in and out of stalls and the milking section, and may potter over a ramp to real-life pasture on the land.
Also on the ground floor, water from the cows' urine will be purified and used to grow red clover, alfalfa and grass under artificial light. Some dung will be despatched to a nearby farm.
Beladon muses on its website about world population growth and the resulting rise in demand for food.
"The big question is how and where shall we produce this food and how healthy will the food be?
"One billion people suffer from [malnutrition]. Food production for a growing world population is an immense challenge. The area of arable land is decreasing while cities are grow with the demand for housing. Citizens are further and further away from farmland."
The floating farm will produce and handle fresh milk very close to the consumers in the city, it says.
"We reduce the transport and logistics and save the environment from greenhouse gases.
"Besides our daily dairy production we emphasise education on healthy food for children and other visitors... on guided tours.
"Floating farm offers a transparent... view of the entire process of milk handling, animal welfare and robotics."
The website says the floating farm will open in January 2017.
One question Beladon faces is do cows get seasick?
"They won't here," says spokesman Minke van Wingerden. "In Friesland, where I come from, sometimes they bring cows from one place to another on a barge. [The floating farm] will be very stable. When you are on a cruise ship, you aren't seasick."
