Pu'u Pehe Islet (Sweetheart Rock) is a tall basalt sea stack located near Manele / Hulupoe Bay just offshore from the main island of Lanai in Pu'u Pehe cove, which includes a sand beach on the west side of the cove and precipitous sheer walls on the east side. Pu'u Pehe is a small islet about 1.6 acres in size reaching a height of about 100 ft. The islet has a flat top area and a sloping area towards the east. There are loose blocks of basalt with pockets of soil. The north and west sides have sheer cliffs. A wave worn bench with tide-pools lie below. There is a heiau on the top of the islet. Several non-vegetated rocks lie nearby the islet. This islet is closed to the public.

Pu'u Pehe Islet is mostly a dry grass and shrubland, dominated by buffel grass (Cenchrus ciliaris) and sandbur (Cenchrus echinatus), with lima (Sida fallax) shrubs interspersed among the grasses. The islet could probably support a couple to a few hundred birds. Some insects on Puu Pehe include ants, garden spiders (Argiope sp.), honey bees (Apis mellifera) visiting ilima flowers, paper wasps (Polistes spp.), uhaloa moths (Eublemma accedens), Hawaiian beat webworms (Spoladea recurvalis), and small cricket-like orthopterans.