US dairy farmers have a new threat to their business - heat waves.
But the "floating farm" in Rotterdam is back in the news for all the wrong reasons.
Concerns about animal welfare have again been raised after two cows on the farm in Rotterdam's harbour fell into the water.
A local animal rights group says that it had tried and failed to get a majority in the city council to withdraw the farm's operating permit, calling the project "madness".
The floating farm is promoted as sustainable, recycling the animals' waste on site, and giving an example of urban farming that could produce more food within cities of the future.
But calls for the farm to be closed are growing louder after a second cow fell into the water and had to be rescued recently.