EarthCaches do not contain a physical container or logbook. Instead, they teach you about geology through real world observations. All observations can be made from the posted coordinates. Optional trailhead coordinates are provided if you wish to explore the fishpond further.
 

SAFETY NOTES: ⚠️ Stay on firm ground,  keep children close,  avoid the water’s edge, and ⚡ watch for slippery or uneven surfaces while exploring the pond area, especially during heavy storms.

Logging Tasks
To claim this EarthCache , you must first visit the posted coordinates and then send your answers through the Geocaching.com Message Center. Please answer the following questions based on your observations and the information provided in the short EarthCache lesson below:

1. Salinity Clues – Based on plant life, water color, or wildlife present: Does the pond appear more freshwater, brackish, or marine today? What clues lead you to your conclusion?
2. Geological Setting – Observe the surrounding terrain. How does the landscape around the pond reflect its volcanic origin? (Think about slopes, rock types, soil color, or the shape of the coastal plain.)
3. Fishpond Type Confirmation – Using the lesson below: Explain why Punawai is classified as a loko wai rather than a kuapā or puʻuone type pond. What features support this classification?

 A photo of yourself or your GPS is optional.

 Leveraging Geology for Fresh, Local Seafood

Hidden behind a neighborhood gymnasium , beside a broad‑limbed mango tree 省 and a field of tall grasses , lies a window into one of Hawaiʻi’s most remarkable innovations in applied geology: the loko iʻa, or Hawaiian fishpond. The quiet basin before you—now partially filled with sediment and vegetation—was once a thriving loko wai, a freshwater‑dominated pond that supported fish and other aquatic life 戀 for the surrounding community.

Though it may appear modest today, this pond represents centuries of engineering knowledge, hydrological insight , and an intimate understanding of volcanic landscapes. 

For generations before seafood markets existed, Hawaiian communities built fishponds to ensure a reliable, sustainable supply of fresh fish close to home. These systems were not simple holding tanks—they were living, dynamic ecosystems designed to work with natural geological processes. The Punawai pond is a prime example of how Hawaiians leveraged the island’s volcanic foundation, groundwater flow, and coastal hydrology to cultivate food in a predictable, renewable way. 

 Geology + Hydrology = Aquaculture

The Punawai pond sits on the basaltic shield of West Maui Volcano, a deeply eroded volcano composed of thick, permeable basalt flows. 直 These basalts act like a sponge: rainfall in the highlands ️ infiltrates the rock, travels downslope through fractures and pore spaces, and eventually emerges at the coast as groundwater springs—called pūnāwai.  These springs are the lifeblood of many Hawaiian fishponds.

At Punawai, freshwater from these springs once welled up into the basin, mixing with seawater  that seeped inland through coastal sediments. This created brackish water, a blend of fresh and salt water ideal for raising species such as ʻamaʻama (mullet) and awa (milkfish). 

Because the balance of fresh and salt water shifts with tides, storms, and rainfall, the pond functioned as a natural estuarine laboratory, where salinity changed daily and seasonally. ️

This hydrological gradient—from mountain recharge to coastal discharge—is one of the defining geological processes of West Maui. The region receives some of the highest rainfall totals in the Hawaiian Islands, feeding a robust groundwater system that historically supported numerous springs and wetlands along the coast. Punawai was part of this larger network (See blue grid in picture interconnecting fishponds. Red square is where you are standing). 

隣 Types of Hawaiian Fishponds

Hawaiians developed at least six major types of loko iʻa, each adapted to specific geological and hydrological settings.

Many of these systems used mākāhā, wooden or stone sluice gates that controlled water flow and allowed small fish to enter while preventing larger fish from escaping. 

While Punawai is a loko wai and not a kuapā‑style pond, it still relied on similar principles: controlling water movement, managing salinity, and harnessing natural groundwater inputs.

直 A Landscape Shaped by Volcanoes and Time

The land beneath your feet is part of the long‑term evolution of Maui’s volcanic system.  Maui was built by two massive volcanoes—West Maui and Haleakalā—whose lava flows eventually met and formed the isthmus between them. Along the northern coast, ancient lava flows created low‑lying plains that later became wetlands, springs, and fishponds. 

Over centuries, the landscape has continued to change. Sedimentation from upland erosion, altered stream pathways, and human land use has gradually filled many coastal ponds. At Punawai, sediment has buried portions of the original pond walls and reduced the flow of freshwater springs. ️➡️直

What you see today is only a fraction of the pond’s former size and depth. Yet even in its quieter state, Punawai remains a powerful example of how geology shapes ecosystems. 

 Sources

This EarthCache utilized Microsoft Copilot to sprinkle in emojis and make the text easier for kids and families to read, helping everyone enjoy EarthCaches even more! . To learn more about Hawaiian fishponds and how geology was leveraged to build them, visit:

• https://waipuni.weebly.com/punawai-a-hui-loko.html

• https://pubs.usgs.gov/publication/70161784

• https://www.seagardens.net/lokoia

• https://www.researchgate.net/publication/247843138_Aquaculture_in_Ancient_Hawaii

• https://kaupomaui.com/research/springs/

• https://www.hostpark.io/hawaiian-aquaculture

• https://seagrant.soest.hawaii.edu/the-return-of-kuula/