The Great Barrier Reef has not lost its power to surprise and overwhelm the senses, it seems. Australian scientists have just discovered a detached coral reef so tall that it dwarfs skyscrapers such as London’s Shard – and it’s the first to be discovered for more than 120 years.

The blade-like, 500m-high reef was found in the northern Cape York area of the GBR on 20 October by an international scientific team, led by marine geologist Dr Robin Beaman from James Cook University, Townsville.

They were working from the Schmidt Ocean Institute (SOI)’s research vessel Falkor, now in the last month of a year-long seabed-mapping expedition in the seas around Australia.

On Sunday (25 October) the team followed up with a live-streamed dive using the institute’s underwater robot SuBastian. A four-hour recording of the high-resolution footage obtained can be seen here.

The base of the newly discovered reef is 1.5km wide and at its peak it reaches to within 40m of the sea surface. Seven other tall detached reefs were already known about in the GBR by the late 19th century, including Raine Island, considered the world’s most important green turtle nesting area.

“We are surprised and elated by what we have found,” commented Dr Beaman. “To not only 3D map the reef in detail, but also visually see this discovery with SuBastian is incredible.”

“This unexpected discovery affirms that we continue to find unknown structures and new species in our ocean,” said SOI co-founder Wendy Schmidt. “Thanks to new technologies that work as our eyes, ears and hands in the deep ocean, we have the capacity to explore like never before.

“New oceanscapes are opening to us, revealing the ecosystems and diverse life-forms that share the planet with us.”

The California-based SOI is a private non-profit foundation established to advance oceanographic research.

This year in the course of the expedition it has discovered deep-sea coral gardens, the longest recorded sea creature – a 45m siphonophore – and up to 30 new species off western Australia, as reported on Divernet. To the east it has found five undescribed species of black corals and sponges and made the first sighting of a rare scorpionfish in Australian waters.

The Falkor’s voyage is set to continue until 17 November, with the extensive seabed maps created to be made available through the Ausbed programme.