Coral Reef Project: Molokaʻi

Science Center Objects

As part of the USGS Coral Reef Project, recent USGS work on Molokaʻi includes looking into the coral record to find clues to past sedimentation events.

View of island from the sky shows its terrain and some puffy clouds above it.

Multi-spectral LANDSAT 8 and ASTER satellite imagery provided by the US Geological Survey and NASA.


The Friendly Isle of Molokaʻi encompasses 673 sq km (260 sq mi), making it the fifth largest of the main eight Hawaiian Islands. The north and west coasts of the island have little coral growth due to impact from northwest swell. However, protected from the southern swell waves by the islands of Lānaʻi and Kahoʻolowe, the south shore of Molokaʻi boasts the longest continuous fringing reef of the U.S. and its holdings. Studies by scientists at the University of Hawaiʻi's Coral Reef Assessment and Monitoring Program have shown that Molokaʻi has sites with the best coral coverage in the main eight Hawaiian Islands. Yet impacts from sediment run-off into the nearshore ecosystem have also caused areas of degradation of the south Molokaʻi reef.


The USGS has used the south Molokaʻi reef as its test ground for developing benthic habitat mapping methods including remote sensing and underwater videography. Investigations into sedimentation along the south coast involve deployment of instrument packages to measure oceanographic conditions such as turbidity, currents, waves, temperature, and salinity. Recent work on Molokaʻi includes looking into the coral record to find clues to past sedimentation events.

The USGS has many cooperators on Molokaʻi including the U.S. Coral Reef Task Force (USCRTF) Hawaiian Local Action Strategy (HI-LAS) for Land-Based Pollution (LBP), University of HawaiʻiUniversity of WashingtonUniversity of California, Santa CruzAustralian National University, and The Nature Conservancy.

Sky view of the coastline of a mountainous island with a shallow coral reef that has lots of deep holes and channels.

The challenging and complex study environment of Molokaʻi’s (Hawaiʻi) fringing reef.