In the Minato Mirai area of Yokohama, across the street from the major shopping mall and Mitsubishi's museum, an amusement park sits along the water.
I have to return to CosmoWorld again. On my second visit, I bought a high-value ticket because we planned to ride the coaster and Ferris wheel. As I mentioned, those attractions were closed, so I still have that ticket to use.
Yokohama CosmoWorld is across the street from the Minato Mirai mall and underground rail station. The area has a few more attractions, and depending on your interests you could spend between one half to a full day here. It's within walking distance of Yokohama Stadium, and there are a couple waypoints worth checking out between them. Admission is free, but all the rides and attractions have individual charges - and there is no free pass (all-you-can-ride) for CosmoWorld. If you are planning on riding several rides, a high-value ticket offers some savings - but do your research before you buy to determine what, exactly, you want to ride.