Big Corals

Large boulder coral towers over a variety of vibrant coral species on the seafloor. — Big Momma is a hotspot coral and fish community. Image: Matt McIntosh/NOAA

American Samoa is known for large corals. These corals may be hundreds of years old and the area around them teems with vibrant marine life, including various species of fish, sea turtles, and sharks. Schools of colorful reef fish, such as butterflyfish and parrotfish, are commonly seen, making it a hotspot for underwater photography.

If you want to snorkel to see large corals, check out Fagatele Bay. There are a number of large massive Porites corals here in shallow water just over the reef margin. The tops of some of these corals reach almost to the surface, providing a close up look at their structure. The large Porites corals are also a favorite spot for some of the larger fish to hang out. You’ll see snappers and sweetlips hiding under ledges, schools of small damsels swimming above smaller branching corals, and parrotfish and butterflyfish feeding nearby. You may even spot a pufferfish snacking on the Porites corals.

Other large corals include Acropora hyacinthus table corals. These corals grow faster than the Porites corals and can be over ten feet across.

Large Corals at Fagatele Bay

Large yellow boulder corals sit on the shallow seafloor with sun rays shining through the surface of the ocean. — Large *Porites* corals at Fagatele Bay can be seen just beneath the surface, and are an excellent sight for snorkelers to see. Image: Kevin Hollerbach

A scuba diver swims down towards a colony of large boulder corals on the seafloor. — A scuba diver explores underwater at Fagatele Bay and is met with a colony of large *Porites* corals. Image: Joe Paulin/NOAA

A scuba diver holds a camera and swims across large table corals that sprawl out from beneath the diver and beyond into the underwater landscape. — In addition to boulder corals, Fagatele Bay has large table corals that spread out over the seafloor, providing a home and safety to a variety of fish and invertebrates. Image: NOAA

Valley of the Giants

Four scuba diving scientists float vertically above two large boulder corals with two extra scuba tanks floating in the water column. — Scientists completing their decompression stop above some of the big corals in the Valley of the Giants in Ta’u. Photo: J. Leonard/NOAA

The largest corals in the sanctuary are in the "Valley of the Giants," a remote region located within the protected waters of Ta‘ū. The name comes from the massive coral heads found in this area. These coral formations can be several meters high, some of the largest in the world, creating a breathtaking underwater terrain. Several corals within the sanctuary are over 30 feet across. The largest coral in this area is known as “Big Momma”.

Satellite map depicting coral locations within the sanctuary area near Ta‘ū Island. A large star marks 'Big Momma,' one of the world's largest known coral colonies, while smaller circles indicate other big corals along the coastline. The map includes a legend in the top-right corner and a scale bar at the bottom-left. — Map showing the density and location of large corals in an area within the Taʻū sanctuary unit known as the “Valley of the Giants.” This was mapped in partnership with Coral Reef Advisory Group and National Park of American Samoa. Image: NOAA, ESRI

For thousands of years, the Valley of the Giants has been limited from human impacts by its remoteness. However, increasing threats such as ocean acidification and rising water temperatures may threaten the future of these centuries old corals.

Coral Etiquette

If you visit these corals, please keep your distance and do not touch corals so they can continue to grow. See sanctuary-wide regulations here.

Big Momma

"Big Momma" is one of the oldest and largest known coral colonies in the world. Located in the Taʻū unit of National Marine Sanctuary of American Samoa, it's a massive Porites lutea coral colony. This type of coral grows very slowly, sometimes as little as 0.39 inches (1 centimeter) per year. This means that large colonies are among the oldest life forms on earth.

Size: Big Momma is estimated to be more than 500 years old and measures over 21 feet (about 6.4 meters) tall and 135 feet (41 meters) in circumference, making it a remarkable natural feature. Explore this virtual dive experience around “Big Momma” to get a sense of the size of the coral.

Species: Porites lutea is a species that is part of the Porites genus, known for forming large, slow-growing colonies that can live for thousands of years.

Location: Big Momma can be found in the Valley of the Giants at the Ta‘ū unit of the National Marine Sanctuary of American Samoa, which protects some of the most pristine and ecologically rich coral reefs in the world.

Ecological Importance: As a large and ancient coral, Big Momma provides critical habitat for a variety of marine species, including fish, invertebrates, and other reef-dwelling organisms.

Because of its size, age, and ecological role, Big Momma coral serves as an important indicator of reef health and is a key focus of conservation efforts in the region.