Scientists are currently mapping and studying parts of the Pacific Ocean floor that have never been examined in detail, and recent expeditions have produced a wide range of findings, from deep-sea ecosystems to fossilized shark teeth. Researchers from the National Oceanic and Atmospheric Administration (NOAA) are using sonar to create more complete maps of the seafloor between Hawaii, Guam, and the Mariana region, while satellite data from NASA and European partners continues to track large-scale ocean changes from space.
The Pacific is of particular interest to geologists because it sits above one of the most tectonically active regions on the planet. According to the U.S. Geological Survey, about 81 percent of the largest earthquakes on Earth occur along the Pacific seismic belt, often called the Ring of Fire. The region is also home to more than half of the volcanoes listed in the Smithsonian Institution’s global database, and roughly two-thirds of confirmed eruptions since 1960 have taken place there. These features are not connected by a single fault or magma chamber but are instead the result of dozens of separate tectonic environments surrounding the ocean.
At many of these boundaries, one tectonic plate is being pushed beneath another, a process known as subduction. The Pacific Plate itself moves at rates exceeding 10 centimeters per year in some areas. Near Guam, GPS-based research has measured the plate moving at about 6.3 centimeters per year as it descends beneath the Mariana system. Along the northern Mariana arc, researchers have recorded deep earthquakes reaching roughly 700 kilometers below the surface, tracking the path of the descending plate as it sinks into the Earth’s interior.
The Mariana Trench, where the Pacific Plate bends downward, reaches depths of about 11 kilometers, making it one of the deepest places on the planet. Pressure there exceeds 1,000 times normal atmospheric pressure. In July 2025, researchers published findings from a study of the Kuril-Kamchatka and western Aleutian trenches in the northwestern Pacific. Using the submersible Vindogii, which can descend to about 11 kilometers, scientists explored cold seeps over 23 dives and found dense animal communities at depths between 5,800 and 9,533 meters. The habitat extended over roughly 2,500 kilometers of trench floor. At one site, researchers counted up to 5,813 tube worms per square meter. These ecosystems do not rely on sunlight. Instead, microbes use methane and hydrogen sulfide rising through seafloor fissures to produce energy, supporting worms, mollusks, and other organisms. The researchers noted that similar geological conditions exist elsewhere, suggesting these deep-sea communities may be more widespread than previously known.
Human pollution has also reached these depths. Scientists sampling the Mariana Trench have found microplastic particles at depths of roughly 10,903 meters, with concentrations around 11 to 13 particles per liter of seawater. Sediment samples taken at about 7,180 meters contained up to approximately 2,200 particles per liter of dry sediment, indicating that plastic waste generated at the surface has traveled nearly 11 kilometers downward.
In April 2026, a joint NOAA and USGS survey operating near American Samoa retrieved samples of polymetallic nodules from the deep-ocean floor. These round structures, which form over millions of years as minerals accumulate around a core, contain manganese, nickel, cobalt, and copper. The survey is mapping more than 30,000 square nautical miles of federal waters in the region to better understand the extent of these deposits and the ecosystems around them.
During a separate NOAA expedition in 2026 near the Cook Islands, remotely operated vehicles working at depths of about 5,000 to 5,500 meters found fossilized shark teeth on the seafloor. The mission collected seven teeth across several dives, and additional teeth were left in place. Many exceeded 7 centimeters in length, and the largest measured 13 centimeters. NOAA researchers said the size suggests they likely came from the megalodon, a shark that lived roughly 23 million to 3.6 million years ago and could grow to about three times the length of a modern great white shark. Beyond their size, the teeth are scientifically useful because they absorb trace elements such as neodymium from seawater over time. Analyzing those chemical signatures can help scientists reconstruct ancient ocean movements, and some teeth may have served as nuclei for polymetallic nodule formation.
Satellite observations in early 2026 detected a large pulse of warm water moving across the tropical Pacific. NASA and European partners used the Sentinel-6 Michael Freilich satellite to track rising sea surface heights moving eastward, a signal associated with Kelvin waves. Because warm seawater expands, satellites can detect temperature changes by measuring ocean height. By mid-May, seas near parts of Peru were more than 15 centimeters above long-term averages. By June 8, the pattern was clearly visible from space, and on June 11, NOAA announced that El Niño conditions had developed. The shift involved warm water moving eastward and a weakening of the usual upwelling of cold water along parts of the Americas.
One of the most closely monitored tectonic sections is the Cascadia subduction zone, which runs from northern California to British Columbia. There, the Juan de Fuca Plate is being pushed beneath the North American Plate, and parts of the boundary are stuck. The last major earthquake along the megathrust occurred on January 26, 1700, before seismometers or satellites existed. Scientists reconstructed the event using evidence from both sides of the Pacific. On January 27, 1700, waves of unknown origin reached Japan, where no local earthquake had been felt, creating what became known as an orphan tsunami. Centuries later, researchers found the likely source along the Pacific coast of North America: submerged forests, sudden coastal subsidence, tree-ring dating, and buried tsunami deposits. When geological records were compared with Japanese historical documents, the dates matched. The earthquake generated a tsunami that crossed the Pacific and reached Japan hours later.
Modern instruments have shown the power of large Pacific earthquakes. The March 11, 2011, magnitude 9.0 Tohoku earthquake off northeastern Japan shifted the seafloor and produced a destructive tsunami. NASA later calculated that the redistribution of Earth’s mass shifted the planet’s rotation axis by about 17 centimeters and shortened the length of day by approximately 1.8 microseconds.
The Hunga Tonga-Hunga Ha’apai volcano, mostly hidden beneath the Pacific, erupted on January 15, 2022. NASA instruments measured an eruption column reaching about 57 kilometers above the ground. More notably, the eruption injected roughly 146 teragrams of water vapor into the stratosphere, an amount equal to about 146 billion kilograms. NASA scientists described this water input as unprecedented in the satellite era, and it increased the amount of water already present in the stratosphere by about 10 percent. The eruption occurred through a shallow marine environment, where seawater interacted violently with magma.
The Pacific floor also holds evidence of ancient human history. About 20,000 years ago, global sea levels were roughly 120 meters lower than today, exposing coastal landscapes where early humans could have lived. As ice sheets melted, those areas were submerged. Some archaeological evidence of early Pacific migration may therefore remain underwater. A 2026 study published in Nature Communications examined 13 individuals from a pre-Inca burial site on the Pacific coast of Peru dating back about 1,000 years. Researchers identified family relationships and evidence of long-distance mobility, with one individual linked to northern Peru, more than 600 kilometers away.
The Pacific remains an area of active research. In 2026, ships and robotic vehicles continue to explore places that no human has directly seen. New maps are removing blank areas from charts, and those areas occasionally contain mountains, ecosystems, or geological features that offer evidence of ancient conditions. The ocean covers roughly a third of the planet’s surface, and scientists are still determining what lies beneath it.
