Designed as a recreational area for the 150,000 inhabitants of the garden cities, the lake is home to many water sports activities. During the boat tour, we were very surprised to hear about the existence of a hidden underwater house — the so-called ‘Cockelbockel’. This Jacques Cousteau-inspired piece of architecture is the absolute highlight of the local Sloterplas diving community, and can be found approximately twelve meters below water level. Owner of the Cockelbockel is diving club OJC, which installed the structure back in 1966. At that time it was the ninth underwater house in the world.
Not many people know about the existence of the Cockelbockel, and even fewer people have ever had the chance to enter it. The turbid water can make it hard for divers to find it (some couldn’t even find it and thought it was gone). Experienced divers can get into the Cockelbockel through a narrow hole in the floor. Inside the house, which fits one to two persons, it’s possible to take off your oxygen mask because there’s always fresh air coming down from the outside world. Round windows in the façade allow you to get a panoramic view of the underwater scene.
In the past, divers who had visited the underwater house could request a sticker and a log sheet as a proof of membership of the Cockelbockel ‘elite’. Five decades after construction and installation, the underwater house is still one of the most spectacular attractions for divers. Trips to the Cockelbockel are organized on a regular basis, like on New Year’s Day, when divers literally drink champaign inside the house.
In case you want to explore the Sloterplas and other treasures in Amsterdam’s western garden cities too, the Van Eesterenmuseum is a great starting point. Be sure to check out the agenda for organized boat tours and other activities.