Two kilometres off SH5, this gorge was a spectacular part of the Waikato River until a hydroelectric dam was plonked across the waterway, shutting off the flow. But the floodgates still open at 10am, noon and 2pm (plus 4pm from October to March), releasing 80,000L of water a second for 15 minutes. You can see the water surge through the dam from two good vantage points atop the cliffs.
Drive here or take a leisurely cycle along the river from Taupō (four-hours return; 30km). You might recognise the rapids from the scene in The Hobbit: The Desolation of Smaug, when the dwarves escape from the elves in barrels.