Underwater Volcano Spews Forth A Torrent of Lava, The End Result Is ‘GOT’ Dragonglass

The rapid cooling of the lava by the seawater resulted in a miles-long 'labyrinth' of ethereal volcanic glass.

An illustration of subterranean lava.
Peppy graphics / Shutterstock

The rapid cooling of the lava by the seawater resulted in a miles-long 'labyrinth' of ethereal volcanic glass.

An underwater volcano located in the Mariana Trench erupted sometime between 2013 and 2015, spewing forth molten lava that spanned a length of nearly five miles on the ocean floor. However, what’s really neat about this geological occurrence is that when the cool ocean water hit the lava — and rapidly hardened it — the end result was “dragonglass,” a material made famous on HBO’s Game of Thrones.

According to GOT lore, dragonglass and Valyrian steel are the only weapons powerful enough to kill the show’s walking dead — or White Walkers as they are known on the show. And in a story something like the huge store of obsidian found deep below our own ocean surface, Game of Thrones character Samwell Tarly found out in Season 7 that a huge amount of dragonglass was located beneath the Citadel in the fictional world of Westeros.

Dragonglass, or obsidian as it is commonly known, is also formed by volcanoes on land by pretty much the same process that the deep sea volcano in the Mariana Trench took advantage of. And although dragonglass is a concept of fantasy, obsidian is real — and that’s what dragonglass actually refers to in the famous fantasy novels. Obsidian is an ebony, vitreous substance, and its hard and brittle properties allowed it to be used as weaponry throughout history.

People fashioned arrowheads, blades, and spears for “hundreds of thousands of years” from it, according to Forbes. That being said, it’s easy to understand why George R.R. Martin chose the formidable material to be used as a weapon against White Walkers in the GOT story-line.

Obsidian is also commonly found in jewelry and rock shops, and when it is polished, it is quite elegant.

Pic of polished snowflake obsidian
Snowflake obsidian. By Memecry2 / Wikimedia Commons (CC BY 3.0)

Researchers came upon the breathtaking network of black obsidian in the Mariana Trench, per Smithsonian Magazine, during a dive in 2015. The original mission was to find hydrothermal vents that weren’t readily visible using submersible robots. They quickly abandoned that mission when they found the fantastic volcanic deposits.

The find is important because much of what we know about submarine volcanoes comes from studying very old, and perhaps even ancient, subjects. The network of obsidian found in the Mariana Trench is relatively young, and it will provide researchers insight into the lava that produced it, along with its associated thriving “biological communities.”

Advanced technology available now may aid scientists in discovering similar networks of obsidian, according to Bill Chadwick, an Oregon State University marine geologist. Chadwick, who led the team that made the find, stated that one submarine volcano — the Axial Seamount — will provide a similar opportunity. The Axial Seamount has erupted “three times in the last 20 years and is due for another eruption within the next several years.”

The finding of the labyrinth of obsidian, which is located almost three miles below the surface, was recently documented in the peer-reviewed Frontiers of Earth Science.