BlueCity: Former waterslide park and swimming pool becomes a hub for sustainable entrepreneurs

A former waterslide park and swimming pool in Rotterdam has become a sustainability hub where  entrepreneurs are sharing their knowledge, expertise, and recycled materials – creating a world in which waste is valuable.

The hub, BlueCity, has been described as a “playground for circular companies”. Located in the building which once housed Tropicana, a subtropical swimming pool and waterslide park along the Maas river, a range of sustainable and circular entrepreneurs have settled down between the slide, the hot tubs and changing rooms, giving a new function to the deserted swimming pool.

BlueCity is home to a greenhouse, beehives, a restaurant and bar, and workspaces for furniture makers and businesses geared towards upcycling, among other businesses. Part of the old pool has become a restaurant. The old changing rooms of the former Tropicana swimming pool are now being used as a dry and wet lab. The combination of these facilities at BlueCity Lab creates the opportunity to make new materials on a cellular level, and develop them into a final prototype.

BlueCity said: “In BlueCity we offer (starting) circular entrepreneurs space, guidance and a dynamic network. This gives feasible and scalable plans the chance to grow into the size they need to have a real impact. In this way we create a circular economy together with entrepreneurs, researchers, local residents, government and education, we close loops and form the city of the future. We are building a world in which the concept of waste does not exist.

“BlueCity is called BlueCity because it is largely based on the principles of the blue economy: we work with what is locally available, assume cooperation instead of competition and generate different income streams, for example by using output from one process as input for another process – all exactly as nature works. We also cross the circles of the circular economy so that networks emerge; which we connect again. All this with the same goal: continuous innovation, creating jobs, reducing the waste mountain by seeing ‘waste’ as a raw material and building social capital without depleting the environment.”

Each of the entrepreneurs based in BlueCity connect their residual flow in different ways. Coffee brewing by Aloha Bar, which roasts its own coffee, serves as a perfect breeding ground for oyster mushrooms grown in BlueCity’s on-site greenhouse, RotterZwam. The dregs of each cup of coffee served at Aloha are used to create a rich fertiliser for mushrooms, which in turn are used as the main ingredient in the restaurant’s vegetarian bitterballen-filled croquettes. The CO2 that is released during this process is used by Spireaux for the production of spirulina. The mycelium is used to develop packaging materials in the BlueCity Lab.

Other examples of circular practices at BlueCity include the beeswax, gathered by urban beekeeper, Stadsimker Abderrahim Bouna, which is then used by furniture maker OKKEHOUT, who make furniture from recycled wood. Plastic waste, which is collected from the neighbourhood by Community Plastics, is recycled into new products for the community such as ovoid birdhouses.

Fruit waste from the market is transformed by Fruitleather into a leather-like material for bags. The worms in the basement ensure the processing of cardboard and organic waste and the aquaponics system provides BlueCity with fresh air. While KEES processes bicycle and car tyres into accessories, all made by disadvantaged people, helping them to gain employment inside or outside BlueCity.

The glass-domed Tropicana closed its doors in 2010, before reopening in 2016 as BlueCity. The building was left empty for several years, until Rotterzwam co-founder Siemen Cox decided to do something about it. He recalls: “I was just driving by this building, and I thought, Hey, this is a big, empty greenhouse that we have in the middle of the city, let’s do something there.”

Siemen Cox originally reached out to the owners of the building about using the space for aquaculture and vertical farming. While the owners wanted the former swimming pool to be used as an events space, they offered Siemen Cox a good price on the basement – a damp, humid area perfect for growing mushrooms. Rotterzwam now sustainably grows mushrooms and delivers 75 kilograms of mushrooms every week to over 20 restaurants in and around Rotterdam.

The Dutch start-up soon came up with a plan to go far beyond mushrooms and start a whole circular city. Seeing the potential in waste, investor Wouter Veer then bought the building for 1.7 million euros to develop it into BlueCity. Blue City is now home to 16 circular businesses and is continuing to grow.


Rosa Medea is Life & Soul Magazine’s Chief. She writes about sustainable lifestyle and green living for publications, and offers content services to planet-friendly businesses. Find out more at 


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