Kings Island new $22 million Diamondback roller coaster features a spectacular splashdown ending. Diamondback will be the tallest and fastest roller coaster at Kings Island. The ride stands 230 feet at its highest point with a first drop of 215 feet at a 74-degree angle. Diamondback has 10 vertical drops, two helixes and a hammerhead turn. Riders will snake their way around 5,282 feet of track at speeds up to 80 miles per hour. The ride opens April 18.