The 5,788-foot (1,764 m) summit rises above the Puʻu Kukui Watershed Management Area, an 8,661-acre (35.05 km2) private nature preserve maintained by the Maui Land & Pineapple Company.

The peak was formed by a volcano whose caldera eroded into what is now the Iao Valley.

Puʻu Kukui receives an average of 386.5 inches (9,820 mm) of rain a year,[2] making it one of the wettest spots on Earth[3] and third wettest in the state after Big Bog on Maui and Mount Waiʻaleʻale on Kauai,[4] Rainwater unable to drain away flows into a bog.

[5] Puʻu Kukui is home to many endemic plants, insects, and birds, including the greensword (Argyroxiphium grayanum), a distinctive bog variety of ʻōhiʻa lehua (Metrosideros polymorpha var.

Due to the mountain peak's extreme climate and acidic peat soil, many species, such as the ʻōhiʻa, are represented as dwarfs.