Black Lily Waterpark

The Black Lily Waterpark is a waterpark in Japan owned by the Black Lily Advanced Materials Laboratory.

The park was built on a site that originally only had a small closed down pool but Mr President bought the place sometime before Chapter 81 for cheap and renovated the whole place into a Liminal friendly health resort, which is also open to humans. Suu's mother was instrumental in the construction of the water park, not least because of her ability as an Undine to create infinite water, which reduced the park's water bill to zero.

The "lazy river"
The Lazy River is a large circular pole in the center of the water park with a gentle current. It is only for relaxing and visitors can either swim freely in the pool or can float on floating mattresses. It is likely, but not confirmed, that the floating mattresses are offered by the park operators as a service to the visitors.

In the middle of the lazy river is a center section where Suu's mother often sits in a chair. There is a bridge in each of the four cardinal points that visitors can use to reach the center section on foot, although the bridges were still unfinished when the park pre-opened in Chapter 81.

Filtration room
The filtration is behind the center section of the lazy river. In this room there is a filtration system in which a Slime girl works as a living water filter. According to Mr President, the filter system is so good that there is "no way" for the pool water to get dirty.

Slime Pool
The "Slime Pool" is the newest attraction of the waterpark and was only built after the final-opening test. It is a pool built specifically for the filtration's Slime girl, due to her overexcited nature, to use to burn off her extra energy so that further incidents in the "Lazy River" can be avoided.

The Slime Pool also appears to be open to visitors to the park, although Kimihito and Centorea initially feared that it would be more like a "sexual harassment pool" due to their personal experiences with Suu. However, this concern apparently turned out to be unfounded as it is the experiences in Suu's surroundings that are the reason why she always gropes people, while the filtration's Slime is more straight laced compared to her.

Trivia

 * While the pool renovation was pre-planned, the actual project and concept of the water park as a Liminal friendly resort only came about at the proposition of Suu's mother after she visited Mr President in his office and asked him to make a place for her to stay. For this reason, the Black Lily Waterpark not only serves as an attraction and source of income for the Black Lily Laboratory, but also as a place for an Undine to use for her elemental water abilities.