Forgotten Underwater Forest Breathes New Life

Once a denuded seascape, California’s Pacific kelp forests in the USA are roaring back to life — thanks to an intense cleanup campaign that is reshaping underwater ecosystems.

“We call it the forgotten forest,” said Tom Ford of the Bay Foundation, likening the submerged regrowth to a long-lost cathedral of green.

Over the past 13 years, divers have spent more than 15,575 hours underwater, removing 5.8 million purple sea urchins across 80.7 acres (32.7 ha) of formerly barren ocean floor. The urchins, which exploded in number after the loss of predators like sea otters, had eaten kelp down to bare rock. By culling them, divers give the ecosystem breathing space — and the smashed urchins quickly become food for other marine life. Within months, kelp forests are regrowing, attracting fish, sea stars, and otters back into balance. This project proves that with persistence, even underwater “lost forests” can be revived.