Underwater Resources

A woman scuba diving next to the wreck of an Amtrac amphibious tractor
A sunken Amtrac amphibious tractor, one of the few currently known underwater relics from the 1944 invasion of Guam.

National Park Service

In the week before the July 1944 American invasion of Guam, the U.S. sent Underwater Demolition Teams (UDT) to destroy the obstacles and mines that had been placed on the inner reef flats by Imperial Japanese troops with the intent of deterring the U.S. troops from reaching the shore. Swimmers inspected and measured the obstacle-filled reef, and then returned to destroy the obstacles, sometimes under cover of night. More than five tons of explosives were used, and the teams cleared 620 obstacles.

Over the past eighty years, the remnants of the UTDs work have become a part of Guam’s natural environment.

In 2023, NOAA Ocean Exploration funded the National Park Service to conduct a multi-disciplinary project entitled "Guam: A Biogeographic and Maritime Cultural Landscape Exploration of a World War II Battlefield" on Guam to further understand how the war may have shaped the cultural history and natural environment of the island today.

 

Resilient: War in the Pacific National Historical Park

Explore War in the Pacific National Historical Park eighty years after the Battle of Guam in this interactive storymap.

 

Learn More about the Project's Discoveries!

 
Scuba diver holding a large underwater camera
The Battle for Guam: 80 Years Later

Video about how the NPS Submerged Resources Center explored the submerged cultural resources from WWII.

The wreck of an Amtrac amphibious tractor on the ocean floor.
Expedition Overview

This project furthers our understanding of one of the most significant invasions of the WWII Pacific theater.

Group of marines wading ashore past airplanes and amtracs
Guam’s WWII Amphibious Battlefield

The project team documented and analyzed remains from the battle still present on the seafloor today.

Hand drawn map showing location of obstacles removed from Asan Beach.
Underwater WWII Blast Artifacts

How did the project team document underwater World War II blast artifacts?

Scuba diver using a metal detector underwater
Technical Divers Give Access to Past

A team of technical divers explored almost 250 targets in search for submerged material related to the 1944 invasion of Guam.

Group of soldiers oversee the unloading of supplies on a beach
Findings "Paved" the Way for Invasion

Project team discovered five sections of pierced steel planking (PSP), also known as "Marston mats," off Agat beach.

A badly eroded beach front covered in tree debris and trash
Measuring Elevation of Coastal Change

Coastal elevation data allow scientists to document how the coastal environment is changing over time.

Scuba diver measuring Amtrac track embedded in coral reef
Using Oral History to Understand Impact

Oral histories shed light on how these landscapes have been affected by World War II.

Last updated: October 29, 2024

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