Sunken Treasure

At Makauwahi Cave Reserve, an open-ceilinged cave holds secrets to the past.

Text by Brittany Lyte | Images By Bryce Johnson

A narrow, three-foot slot in the rock feeds into a high-ceilinged yet dim vault. Crouch down—Watch your head!—and the opening to the limestone cave lends just enough wiggle room for visitors to crawl inside on all fours.

It’s a mildly claustrophobic experience, but the space that follows is surprisingly grand. A wondrous cavern of twisted stalactites opens onto a bluebird sky that nourishes a lush green carpet of native shrubs and palm trees. One reason the heart of this cavernous complex bursts with life is that it has an open ceiling, which allows in plentiful sunshine, rain, and roosting seabirds.

This sunken garden is at the center of Makauwahi Cave Reserve, a 17-acre property that hosts a collection of fish and bird skeletons, snail shells, goat teeth, and hooks carved from bone and pearl shell by early Hawaiians. Formed over a period of nearly 400,000 years, the half-acre cave system, located within Māhā‘ulepū Valley on Kaua‘i’s arid south shore, began as a sand dune, which slowly hardened into a hollowed-out amphitheater of stone. Beneath its surface lie millions of mud-caked fossils of some of Hawai‘i’s rarest plants and creatures, and artifacts belonging to the island’s earliest settlers—a paleontologist’s treasure trove.


Formed 400,000 years ago, the incredible cave system located within Māhā‘ulepū Valley on Kaua‘i’s south shore contains fossils and Hawaiian artifacts.


The largest room of the cave lost its ceiling about 7,000 years ago, when persistent groundwater seepage weakened the stone cupola to the point of collapse. The ceiling crashed down in such dramatic fashion that it created a brackish lake bed. This lake preserved the soil beneath it, and everything that fell into its waters after, including flora and fauna, seeds, pollen, spores, and fragments of Polynesian sailing canoes. In the 1950s, the lake disappeared, and left behind a giant sinkhole with a sedimentary record that can be read, layer by layer, almost like the chapters of a history book. The sediment and relics that remain embedded in the earth represent 10,000 years of civilization.

“Makauwahi Cave may be as close as some of us will ever get to time travel, I suspect,” writes paleoecologist David A. Burney, who manages the reserve and began excavating the cave with his wife in 1995, in his 2010 memoir, Back to the Future in the Caves of Kaua‘i: A Scientist’s Adventures in the Dark. “With hard work, one can coax out of this place a lot of information about the past. … Makauwahi Cave is only one place, but it has lived in many times.”


Near Po‘ipū, Makauwahi Cave is one of the richest fossil sites in the Pacific.


According to Burney, Makauwahi may be the richest fossil site in the Hawaiian Islands, if not in all of the Pacific. The upper crust of the sinkhole floor is a layer of reddish-brown clay that contains artifacts from the present day: Styrofoam cups, bits of plastic, tattered 35-millimeter film. The deeper the layer, which archaeologists access by digging pits along the edge of the sinkhole, the further back into history is captured. Within it are records of floods, droughts, hurricanes, and the early Polynesian diet, as well as chronicles of the coastal area’s cultural and ecological evolution. Almost 30 feet down, an oozing layer of mud preserves the remains of a flightless waterfowl with a bill like a tortoise, an extinct bird that was among the largest land animals on Kaua‘i.

This timeline buried beneath the cave floor has led to dozens of new discoveries about natural disasters, Hawaiian lore, and extinct species, such as the Kaua‘i mole duck, another flightless bird that had a platypus-shaped bill. This year, scientists sifting through deposits of coral fragments concluded from them that a 1586 tsunami on Japan’s Sanriku Coast was triggered by a mega-earthquake in the Aleutian Islands, rather than an earthquake in Lima, Peru, as had been previously believed. This new evidence, revealed by carbon-14 dating, is now helping scientists determine where, and how frequently, earthquakes and tsunamis are likely to strike across the globe. The study’s findings are also informing the re-mapping of Hawai‘i’s tsunami inundation zones.

In addition to hosting archaeological research, the nonprofit that oversees the reserve is working to replace invasive plants on six acres of the property with native species, such as the night-blooming caper plant and the thirsty, long-rooted a‘ali‘i shrub. Nearby, indigenous birds and plants have begun to reestablish themselves due to these restoration efforts.

Along the reserve’s coast is a half-mile nature trail open to the public, which features examples of such native fauna and a view of the Makauwahi sinkhole. Four days a week, the reserve also hosts guided tours of the cave complex, including access to unique features such as stalagmites and false floors. However, smaller chambers remain closed to the public for preservation’s sake, and to prevent visitors from incidentally squashing rare organisms that reside there, like the blind cave wolf spider, which is eyeless.


The complex cave system’s massive sinkhole give archaeologists, volunteers, and visitors a significant glimpse into Hawaii’s history before the first Hawaiians settled in the area. At 17 acres, Makauwahi Cave Reserve is the largest limestone cave found in the Islands.


In Hawaiian, Makauwahi means, roughly, “smoke eye.” As legend has it, the cave was occupied in the mid-19th century by a soothsayer who was known to spark a small fire on a sandbar in the lake, and then look into the wisps of smoke spiraling skyward to find visions of the future.

Whether or not it is true, the anecdote is fitting. More than a graveyard of extinct species and foregone lifestyles, Makauwahi Cave Reserve gives rise to the study of what has been lost, in order to help humankind better understand what lies ahead. opposite: Near Po‘ipū, Makauwahi Cave is one of the richest fossil sites in the Pacific.

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