Imagine if...
we explored a little-known part of the ocean.

The Twilight Zone
is vast, remote, and largely unexplored.

The Twilight Zone
is vitally important to the entire planet.

The Twilight Zone
presents an opportunity to do things right.


From a Bold Vision, Bold Ideas

We are embarking on a journey to explore and understand one of our planet’s hidden frontiers—the ocean twilight zone. Our project will combine exacting science, innovative technology, and broad engagement to turn knowledge into actions that improve understanding of our planet and how to live sustainably on it.

Dive in and get informed

Below the sunlit surface, there’s a realm known as the ocean's “twilight zone.” At 200 to 1000 meters below the surface, sunlight is barely a glimmer, yet flashes of bioluminescence give us a clue that these waters teem with life.

Salps are gelatinous organisms can form chains up to 130 feet long, making them the longest animal on Earth, and often form dense swarms. They feed continuously on organic matter in the water and produce dense fecal pellets that sink rapidly into the depths. Large swarms of salps may be an important part of the global carbon cycle.


In the darkness of the twilight zone, light is an important way for animals to communicate, hunt, find a mate, and avoid being eaten. The light can be almost any color, but blue travels the farthest in seawater before being absorbed. Many bioluminescent organs in fish and other organisms are filled with bacteria that the animals must acquire after birth.


The bristlemouth is a tiny fish only about 3 inches long and is believed to be the most abundant vertebrate on Earth, numbering perhaps in the hundreds of trillions or quadrillions.


Many large predators such as some sharks, whales, and squid make frequent trips into the twilight zone to feed, providing an important ecological link between surface and deep ecosystems.


Anglerfish use a bioluminescent appendage to lure prey close to their mouth, but only the females. Male anglerfish are tiny and attach themselves to their mate, after which their eyes and many of their internal organs wither away.

Join the effort

The time is now for us to better understand our ocean twilight zone before change there becomes permanent and irreversible. But we can’t do it alone. Learn about the ways that you can join our effort and stay informed.

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An Audacious Project


Woods Hole Oceanographic Institution brings together scientists and engineers with a shared vision of asking critical questions about our ocean and developing bold ideas on how to answer them.


The Ocean Twlight Zone is part of The Audacious Project, a new model to inspire change by building a community of supporters who become partners in addressing big challenges with bold ideas.

“This is not just a journey for
scientists; it is for all of us.”

Dr. Heidi Sosik, WHOI oceanographer