They are the mighty rainforests of the ocean, towering up to 25 metres from the seabed.
Like many forests on land, the giant kelp jungles in the waters off south-east Australia are gravely threatened by climate change, scientists say.
Karen Gowlett-Holmes, a marine biologist with the CSIRO and co-owner of Eaglehawk Dive Centre on the east coast of Tasmania, said the destruction of the kelp forests was having ”a huge impact” on marine ecology.