A sustainability hub is being built in an abandoned Rotterdam water park. With bars, beehives and an underground greenhouse, “BlueCity010” has a big draw among the hip and conscious.

Tropicana, just a stone’s throw from the city centre of Rotterdam, used to be a subtropical swimming paradise along the Maas river. An entire generation of Rotterdam natives bobbed in the wave pool and gleefully braved the wild rapids water slide. But this came to an end when Tropicana filed for bankruptcy in 2010.

The building was neglected for years, left to crumble like a rotten tooth along the water’s edge: the brilliant white walls fading and the once-transparent domes turning a milky grey. However, the pompous building, built in the eighties, has been partially restored.

Plastic chairs and picnic tables now surround the old water slide. On a sunny Thursday afternoon, the area is packed with young people wearing trendy sunglasses and brightly colored trainers. Welcome to Aloha Bar, an easy-going joint with bar, restaurant, coffee roaster and riverside patio.

view of BlueCity 010
Ideas with a view: BlueCity010’s prime location.

If you didn’t know any better, you’d think Aloha was just another branch on the ever-expanding hipster tree. But there’s more to this café-restaurant than meets the eye. It’s part of a network of so-called sustainopreneurs who plan to transform Tropicana into a sustainability hub by using recycled materials and waste.

The dregs of each cup of coffee served at Aloha are used to create a rich fertilizer for mushrooms, which in turn are used as the main ingredient in the restaurant’s vegetarian bitterballen, filled croquettes.

sustainable greenhouse in a swimming pool
No life guard on duty.

Urban greenhouse

In the basement, Siemen Cox swings open the door to one of the old changing rooms. On the walls hang large, transparent bags filled with coffee grounds and mushroom spawn. “Oyster mushrooms thrive in this dark, damp environment,” he explains. “These mushrooms will be ready for harvest in just a few weeks.”

Cox used to work in the financial service sector. Then one day, as he was biking past the old swimming complex, he noticed the light filtering through the glass dome and thought: this is the perfect place for an urban greenhouse.

He contacted the owner of Tropicana, an investment company, via LinkedIn. “They planned to use the area under the dome as an event location, but gave me a good price on the basement,” Cox remembers. “So I decided to grow mushrooms there, which thrive in dark places.”

Siemen Cox showing around
Plenty of space for Siemen Cox and his team.

Three years later, his company Rotterzwam (a Dutch play on words meaning Rotterdam fungus) delivers 75 kilograms of mushrooms every week to over 20 restaurants in and around Rotterdam. Cox and his business partner, Mark Slegers, also organize workshops for entrepreneurs interested in starting similar initiatives.

“The iconic quality of the building serves as a spotlight,” Cox explains. “People from around the world are drawn to it. That’s what makes this the perfect place to create an innovative hub where entrepreneurs interested in sustainability can share their knowledge, expertise, and recycled materials.”

Siemen Cox showing mushroom cultures in the basement
Mushroom cultures thrive in the basement.
mushrooms on the walls
food production in BlueCity 010

Self-sustaining cycle

Cox and Slegers plan to make this hub happen with the help of investor ifund and like-minded entrepreneurs. They’re calling it: BlueCity010. “We’ve been talking about a sustainable society for far too long now,” says Cox.

“We not only want to come up with creative solutions, we also want to make those solutions happen; to test ideas and apply them in practice. And we’re not alone. Last year, dozens of entrepreneurs responded to our call to transform Tropicana into a sustainability hub.”

Urban beekeeper Abderrahim Bouna was one of the first entrepreneurs to join BlueCity010. Bouna has beehives across the city, but his home base is Tropicana. He collects honey to eat, to sell, and to make beeswax, which he donates to on-site carpenter Okke, who transforms recycled wood into furniture.

In the small kitchen next to the Rotterzwam culture rooms, Bouna is frying an egg, seasoning it with the oyster mushrooms grown here. “This is what you call a hyper-local lunch,” he says with a smile.

In the short term, Bouna hopes to expand his locally-sourced menu with other vegetables grown using the aquaponics system that BlueCity010 recently acquired. Bouna explains how it works. “The system, which consists of large water tanks filled with fish, pumps the water – and poo – to our vegetable garden. The crops are planted in pebbles, which purify the water. The purified water is then pumped back to the fish and a self-sustaining cycle is born.”

Abderrahim Bouna cooking
Circular economy. Abderrahim Bouna prepares food directly on site.
mushrooms in a pan
Locally sourced mushrooms make for a nice dish.

Make connections

The system demonstrates at the micro level what BlueCity010 hopes to achieve on the macro level: a new, waste-free economy made up of a network of circular systems. “If you look at the Netherlands from above, you’ll see neat little boxes that illustrate our well-defined zoning plan,” explains Siemen Cox.

“One box is for agriculture, one for recreation, and another for industry. We want to make connections; to bring together various functions and utilize residual waste flows. How? By using nature’s innovations and by attempting to replicate the solutions provided by our ecosystem. Only then can we become truly sustainable in everything we do.”

monkey figure in a basin
Abandoned, not forgotten.
interior design of the swimming pool
overall view of the BlueCity 010, the former Tropicana swimming pool