Until the end of World War II, Rotterdam had many floating swimming pools throughout the city. Between 1880 and 1960, floating pools were constructed all around the harbor. These swimming facilities consisted of wooden pontoons with pools floating in the river.

Swimming took place in the natural river water, with men and women swimming separately. The pools were popular as recreational spots but were also widely used for swimming lessons.

During World War II, several of these pools were damaged or dismantled to be used as firewood. By the mid-20th century, it was realized that the water quality of the Nieuwe Maas was not suitable for swimming, and the remaining floating pools disappeared from the city.

In the Netherlands, swimming in surface water is generally permitted everywhere unless explicitly prohibited. Due to safety concerns, swimming is banned in navigable channels, near bridges, locks, and harbors. Additionally, the Inland Navigation Police Regulations prohibit swimming around waterways, bridges, locks, weirs, waiting areas, harbors, or their entrances, as well as at mooring places.

Rotterdam presents an exceptional case: swimming in surface water is also prohibited by the General Municipal By-law (APV). This means that swimming in surface water is banned throughout the entire city of Rotterdam.

To establish a floating pool, factors such as water quality, nautical safety, accessibility, and available space at the quay must be addressed. Using three thematic maps, these aspects are analyzed to identify several suitable locations for a floating pool.

The Nieuwe Maas and the Schie accommodate a mix of inland navigation, sea traffic, recreational boating, passenger shipping, and water transport. This makes these waterways much more hazardous for a floating pool compared to other European cities. From a nautical safety perspective, only the inland harbors are suitable locations for a floating pool, preferably in a harbor that can be closed off with a bridge. This would prevent commercial and recreational vessels from accidentally entering the harbor.

Swimming in surface water requires good water quality. However, this is only monitored at designated swimming locations. The water in the Nieuwe Maas and the Schie is not tested for the presence of bacteria harmful to swimmers. Therefore, it is unclear where in the city the water meets the required standards. It is known that water quality can be affected by factors such as flow rates, the presence of sewer overflows, and wastewater discharge from houseboats.

Ideally, a floating pool should be located near a densely populated area. Additionally, there must be space available on the quay for installing the pool. The map shows areas where there is currently no (or minimal) quay usage, indicating available space. However, this does not guarantee that these locations are nautically safe or actually suitable as berths for a floating pool.

The analysis of the three thematic maps reveals that most of the water is unsuitable for a floating pool. Some locations are already suitable (green). Certain locations require additional measures to accommodate a floating pool (yellow). A few locations are only suitable with substantial modifications (orange).

Instead of opting for a floating swimming facility at a fixed location—a typology already used in numerous cities—Rotterdam could develop a movable concept that adapts to the changing cityscape. This could be a floating pool boat or a modular pool that is dismantled in the winter and set up at a different location each summer. Navigating with water on board is neither simple nor safe, but this could potentially be achieved with a push boat of the type known as a 'beunbak.'

It is still unclear whether a swimming pool boat would be classified as a building or a vessel under the Environmental Planning Act. Further research is needed to clarify this distinction, as it could affect the permits, requirements, and regulations applicable to the swimming pool.