Lots of strange deep-sea creatures, like this anglerfish, have been caught on camera for the first time - hundreds of metres below the surface on the Great Barrier Reef.
Scientists from Australia put cameras on the sea floor - that's a depth of 1,400 metres!
When you're so far down in the ocean, there is very little light. So they had to use really special high-tech cameras that work in the dark.
The cameras were controlled remotely so they could capture some amazing images, like this one of a deep-sea amphipod crustacean.
This is a deep-sea red jellyfish Atolla - the reef where it lives is called Osprey and is part of a conservation zone.
Another jellyfish - a Peraphilla deep-sea one. Recent oil spills and global warming have made it more urgent to study deep-sea life, say scientists from the Deep Australia project.
Here's a hatchetfish. Lead scientist Justin Marshall said: "We simply don't know what life is down there and our cameras can now record the behaviour and life in... the deep-sea."
The special cameras that shot this viperfish are being sent to the Gulf of Mexico, the site of the huge US oil spill. They'll be used to see how the oil has affected deep-sea life there.