With its wide mix of attractions, Summerland attracts families,couples and youngsters. Among the amenities are the Adventure Dome, a covered structure featuring a wave pool; Adventure Lagoon, open in summertime, with water slides and hot tubs; and the Great Journey, a 2,132-foot-long lazy river, said to be one of the longest in Japan. The Spin Dinghy, a unique new ride concept, debuted in April, and the Tower’s Rock water slide tower opened this month.