The world’s largest rays may be plunging to incredible depths not to hunt, but to find their way through the vast, empty ocean.
A new study has revealed that oceanic manta rays—graceful giants with wingspans up to seven meters—can dive deeper than 1,200 meters below the surface, far deeper than scientists once believed.
An international team of researchers working in Peru, Indonesia, and New Zealand tracked these rays using electronic tags to uncover the mystery of their deep dives.
Their study, published in Frontiers in Marine Science, suggests that the dives could help manta rays build “mental maps” of the ocean to guide their long migrations.
Dr. Calvin Beale, who led the research while completing his Ph.D. at Murdoch University, explained, “Far offshore, oceanic manta rays are capable of diving to depths greater than 1,200 meters.
These dives, which are followed by long-distance movements, might help them gather environmental information and navigate across the open ocean.”
Between 2012 and 2022, the researchers attached 24 tracking tags to manta rays at three sites—Raja Ampat in Indonesia, Tumbes in Peru, and Whangaroa in northern New Zealand.
The tags recorded data on each manta’s depth, location, and movement. Eight tags were later recovered after floating to the surface, while others transmitted summary data by satellite. In total, the team collected over 2,700 days of information.
Most of the extreme dives occurred in New Zealand waters, where mantas reached depths of up to 1,250 meters.
These dives often began just after the animals moved off the continental shelf into the deep ocean.
Interestingly, the rays didn’t stay long at their lowest point, suggesting they weren’t feeding or avoiding predators.
Instead, the dives appeared to follow a stepped pattern down and up again, as if the animals were “sampling” the environment layer by layer.
Researchers believe the mantas could be using these dives to sense subtle environmental cues—like variations in magnetic fields, temperature, oxygen, or light—to help them navigate. At great depths, the ocean is more stable and predictable, which might make it easier for mantas to gather consistent signals.
After resurfacing, the mantas often traveled more than 200 kilometers over the next few days, supporting the idea that these dives serve as a kind of orientation exercise.
In contrast, mantas in Peru and Indonesia rarely dived deep, possibly because they live in shallower coastal waters. In New Zealand, however, the seafloor drops away sharply, creating an ideal environment for deep exploration.
“Understanding why manta rays dive so deep helps us learn how they cross vast oceans and link distant ecosystems,” Beale said. He added that protecting these migratory giants will require global cooperation, as they depend on both coastal and deep-sea environments.
“The deep ocean remains one of the least understood parts of our planet,” he said, “yet it plays a crucial role in Earth’s climate and supports life above and below the waves.”
