You’re walking across a jagged, sun-scorched field of ‘a‘ā lava on the Kohala Coast of the Big Island. It’s hot. The air smells like salt and dried kiawe wood. Suddenly, the black rock gives way to a splash of neon green. You look down into a small, jagged opening in the crust and see water. It’s crystal clear, perfectly still, and teeming with tiny, bright red shrimp. You’ve just stumbled onto one of Hawaii's most fragile ecosystems. This is the Waikōloa Anchialine Pond Preservation Area, and honestly, most people walk right past it on their way to the beach without realizing they're looking at a biological miracle.
Anchialine (pronounced AN-key-ah-line) ponds are weird. They aren't quite freshwater, but they aren't seawater either. They are landlocked bodies of water with a subterranean connection to the ocean. Because Hawaii’s volcanic rock is basically a giant sponge, the tides actually breathe through the island. When the tide rises at the beach, the water level in these ponds rises too, even if they’re hundreds of yards inland. It’s a delicate balance of fresh groundwater floating on top of heavier salt water.
The Red Shrimp and the Lava Secret
If you peer into the Waikōloa Anchialine Pond Preservation Area long enough, you’ll see the ‘ōpae‘ula. These are Hawaiian red shrimp (Halocaridina rubra). They’re barely half an inch long. They are survivors.
These shrimp are legendary among biologists because they can live for years—some say up to 20—without much food. They graze on the microbial crust (the "biofilm") that grows on the submerged lava. For centuries, Native Hawaiians used these ponds to gather bait for fishing. It wasn't just a "nature spot"; it was a functional part of the ahupua‘a (land division) system.
But there’s a problem. These ponds are disappearing.
Fast.
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Development and invasive species have absolutely wrecked many of the pond systems across the state. At Waikōloa, the preservation area is one of the few places where you can see the system working the way it’s supposed to. Well, mostly.
What’s Killing the Ponds?
It’s not just climate change or rising sea levels, though those are real threats. The immediate danger is much more mundane: people dumping their pets.
Guppies and tilapia.
People think they’re doing a "good deed" by releasing a pet fish into a pond. It’s actually an ecological disaster. These invasive fish eat the ‘ōpae‘ula. Once the shrimp are gone, the algae overgrows. The pond loses its oxygen. The water turns murky and stagnant. It dies. In the Waikōloa Anchialine Pond Preservation Area, volunteers and scientists from groups like the Hui Loko and the University of Hawaii work tirelessly to pull these invasive species out. It's a constant battle.
Then there's the nutrients. When resorts or homes nearby use too much fertilizer, that nitrogen and phosphorus seeps through the porous lava and hits the ponds. It acts like a shot of adrenaline for the wrong kind of algae. You get these thick, green mats that choke out the sunlight.
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Why You Can't Swim Here
Seriously, don't do it.
I know it’s 90 degrees out and that water looks refreshing. But even the sunscreen on your skin can be toxic to the microbial life that forms the base of this food chain. The oils from your hair, the laundry detergent residue on your swimsuit—all of it disrupts a chemistry that has been stable for thousands of years.
The Complex Reality of Restoration
Restoring a pond isn't as simple as cleaning out some trash. It’s a slow, manual process. You’ll often see groups of local students or conservationists at Waikōloa physically pulling out invasive pickleweed or mangrove shoots.
Native plants like makaloa (a sedge) belong here. The invasive stuff grows faster, deeper, and stronger. It fills in the pond, turning open water into solid ground. Once that happens, the anchialine habitat is gone forever. It doesn't come back.
Interestingly, the University of Hawaii at Hilo has done extensive research on the genetic diversity of the shrimp in these ponds. They found that different pond clusters have distinct genetic signatures. The shrimp in the Waikōloa Anchialine Pond Preservation Area are literally unique to this coastline. If this specific population dies out, you can’t just "restock" it from a pond in Kona and expect it to be the same.
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How to Actually See the Ponds
If you want to visit, head toward the Waikōloa Beach Resort area. There’s a public access trail that winds through the preservation area.
- Go during a high tide. The ponds look much more vibrant when the water volume is up.
- Look, don't touch. Use polarized sunglasses if you have them; they cut the glare off the water so you can actually see the red shrimp dancing on the rocks.
- Stay on the path. The lava around the ponds is often thin and "shelly." Stepping off the trail can crush the hidden crevices where the shrimp hide when the tide is low.
The Waikōloa Anchialine Pond Preservation Area is a reminder that the "real" Hawaii isn't just the white sand beaches. It’s this weird, rugged, inter-connected world beneath our feet. These ponds are the windows into the island's groundwater. If the ponds are healthy, the reef is usually healthy. If the ponds are dying, it’s a warning sign that the whole system is out of whack.
Take Action: Respecting the Resource
Next time you’re on the Kohala Coast, treat this area like a museum.
- Check your gear. If you’ve been hiking in other parts of the island, wash your boots. You don't want to carry seeds from invasive plants into the preservation area.
- Support local groups. Organizations like the Hawaii Island Land Trust or the The Nature Conservancy often have volunteer days or educational talks about these specific ecosystems.
- Spread the word. The biggest threat to the Waikōloa ponds is ignorance. When people understand that these aren't just "mosquito holes" but are rare, tide-driven ecosystems, they tend to treat them with a lot more respect.
These ponds have survived volcanic eruptions and centuries of change. With a little bit of space and a lot less invasive fish, they’ll be here for another thousand years. Just keep your goldfish in their tanks and your feet on the trail.
To see the ponds in person, park at the Anaeho'omalu Bay (A-Bay) public parking lot and follow the signs for the historic trail. The walk is easy, but the sun is brutal, so bring water—just don't spill any in the ponds.
Practical Next Steps
To experience the Waikōloa Anchialine Pond Preservation Area responsibly, begin by downloading a tide chart for the Anaeho'omalu Bay area to ensure you visit during peak water levels. When you arrive, locate the educational kiosks at the trailhead; they provide updated information on recent restoration efforts and specific bird species, like the ae‘o (Hawaiian stilt), currently nesting in the area. Always carry out all trash and report any sightings of people dumping fish or swimming in the ponds to the local Department of Land and Natural Resources (DLNR) office. Support the ecosystem's longevity by choosing mineral-based, reef-safe sunscreens for your entire trip to minimize chemical runoff into the groundwater system that feeds these fragile habitats.