Scientists have discovered a massive seamount beneath the Pacific Ocean, though any secrets hidden deep within it remain unknown, according to new research.

Lurking some 3.2 miles (5.1 km) beneath the Pacific Ocean, the seamount is about two-thirds of a mile high (1.1 km), though it appeared "out of the blue" for researchers who were mapping the US continental shelf nearby.

Seamounts are rocky leftovers from extinct, underwater volcanoes, and can be found on ocean floors around the world. This one was discovered about 186 miles (300 km) southeast of Jarvis Island, an uninhabited island located in one of the least explored parts of the South Pacific Ocean, experts say.

"These seamounts are very common, but we don't know about them because most of the places that we go out and map have never been mapped before," James Gardner, a University of New Hampshire research professor who works at the university's NOAA Center for Coastal and Ocean Mapping/Joint Hydrographic Center, said in a statement.

Gardner and his colleagues used sonar technology to find the underwater mountain instead of typical low-resolution satellite data, which is not advanced enough to detect most seamounts on the ocean floor.

"Satellites just can't see these features and we can," Gardner said.

Researchers have yet to explore the effects of this yet-unnamed seamount on the surrounding environment, though they have observed a host of diverse marine life, such as commercially important fish species, living within it, Live Science reported. However, the newly found seamount is too deep underwater to provide a home for rich fisheries, Gardner noted.

"It's probably 100 million years old," Gardner said, "and it might have something in it we may be interested in 100 years from now."

The research team made the discovery aboard the R/V Kilo Moana, an oceanographic research ship owned by the US Navy and operated by the University of Hawaii.