Punalu'u Beach, Black sand beach in Kaʻū, Hawaii, United States

Punalu'u Beach is a stretch of dark volcanic sand on the southeastern coast of Kau in Hawaii. Fine black grains cover the shore where lava once flowed into the ocean, cooling quickly and forming a smooth surface framed by coconut palms and turquoise water.

Three pre-contact heiau stand near Punaluʻu, including Kaʻieʻi.e., a fishing shrine on a bluff above the old Ninole fishponds, and the Halelau/Kaneʻeleʻele complex overlooking the bay, whose western edge was cut away in 1906 for a sugar company wharf and warehouse. Missionaries reached Kaʻū as early as 1833, and Hōkūloa Church, a memorial chapel and graveyard, sits on the ridge above the beach near the birthplace of Henry ʻŌpūkahaʻia (1792–1818).

The name Punaluʻu comes from the Hawaiian puna luʻu, "spring water diver for": during droughts, Hawaiians dived with a jug to fetch the cold fresh water welling up through the sand. Three pre-contact heiau stand nearby, including Kaʻieʻi.e., a fishing shrine on a bluff above the old Ninole fishponds.

The park offers parking, restrooms, outdoor showers, and covered picnic tables for day visitors, plus designated spots for campers who obtain a permit. A boat ramp provides access to the water for small watercraft.

Hawaiian green sea turtles and hawksbill turtles come ashore regularly to rest on the warm black sand. Visitors can watch them from a few meters away as they regulate their body temperature.