Lake Winnepesaukah has the oldest ride of what type, which finishes with a climactic splashdown?
Lake Winnepesaukah:  Its Boat Chute attraction, designed by Carl Dixon, opened in 1927 and is the oldest mill chute water ride of its kind still in operation in the United States. Old Mill (ride):  While generally considered a gentle ride, a variation that ends with a climactic splashdown, similar to the modern-day log flume, is known as a mill chute.
i don't know