Inferno Crater Lake is a large hot spring located in the Waimangu Volcanic Rift Valley on the North Island of New Zealand, and the largest geyser-like feature in the world.

At low water levels the lake can be a dull grey colour, changing to an intensely sky blue colour at higher lake levels, in particular after the overflow stage.

[5] Since 1901 the lake occupying Inferno Crater has exhibited water-level variations closely associated with the Waimangu Geyser cycle.

[5] Inferno Crater Lake and its neighbouring Frying Pan Lake form a unique relationship and follow an interconnected rhythmic cycle of hydrology variations repeating itself over the course of roughly 38 days.

Next, the lake overflows for about 51 hours at a rate of almost 80 litres per second (0.080 m3/s; 21 US gal/s), discharging on average 140,000 cubic metres (140 million litres; 37 million US gallons) of over 70 °C (158 °F) hot water down a temporary overflow stream into Waimangu Stream in the valley below.