At Ha'akulamanu (Sulphur Banks), volcanic gases seep out of the ground, along with ground water steam. These fumes can be amazingly hot. In 1922, scientists drilled two holes to measure underground heat in the area. Temperature measurements remained constant at 205° F (96° C) down to 50 feet (15 m), the maximum depth drilled. Fumes emitted here include sulfur dioxide (SO₂), which smells like a struck match, and hydrogen sulfide (H₂S), the gas that smells like rotten eggs. These two gases react chemically to produce pure sulfur, a yellow mineral known to Hawaiians as kūkaepele, the waste of the volcanic deity Pele.

Take a short day hike to Haʻakulamanu (Sulphur Banks)
Learn more about the phenomenon of Steam Vents and Sulphur Banks