If you happen to have a yacht handy and it's just not enough fun on its own, then you need the Freestyle Cruiser Inflated Water Slide.
This is the first ever sealed air, custom, inflatable water slide meant for the yacht industry. Now you can turn your already-badass personal house boat into a water park without the giant line ups. The company states that there is no "off the shelf" option for getting the Freestyle Cruiser, but rather that each is custom-sized according to your yacht.
The water slide comes in either a leg-supported version or a non-leg supported version, but the latter is not recommended for yachts spanning over 5 meters.
Yacht-Side Water Parks
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Massive Floating Playgrounds
Japanese Crowd Surfing
Horrifying Hide-and-Seek Ads
Infinite Waterslide Advertising