Dive below the surface into Sydney's hidden forest beneath the waves for this year's CNN Call to Earth Day.

Join professional surfers Laura Enever and Tom Carroll as they explore the restoration efforts of SeaTrees, Operation Crayweed, and Sydney Institute of Marine Science in bringing back the once-vanished kelp forests on Australia's eastern coast.

Crayweed once formed dense beds on shallow reefs along the Sydney coastline. These underwater forests have become locally extinct, causing detrimental repercussions for native fish, abalone, crayfish, and coastal marine biodiversity. Crayweed is among the most important ecosystems on the planet, providing critical food and habitat for hundreds of species.

These vast underwater forests support coastal food webs, sequester immense amounts of atmospheric carbon, produce oxygen for marine life, and support unique coastal biodiversity, which is not supported by any other seaweed species.