Puhimau pit crater is about 160 m deep. The crater probably formed between the mid-15th century and A.D. 1800. No eruptions have occurred from Puhimau Crater, and no lava flows from historical eruptions have poured into the crater. Dense forest surrounds the crater, but a small thermal area lies just north of the crater. Steam often can be seen low on the northwest wall.
--- http://hvo.wr.usgs.gov/gallery/kilauea/erz/uppererz.html