At age 53, explorer Victor Vescovo has already climbed the world's seven highest peaks. Now he is on a mission to explore the bottom of the ocean - a treacherous territory that remains largely untouched by humans.
"I think it's almost cliche at this point, how people mention that 70% of the Earth is ocean, and we've only explored 5% of it," Vescovo told Business Insider.
That fact inspired Vescovo's quest to visit the deepest points of all five oceans - a mission appropriately called the Five Deeps Expedition.
In December, Vescovo became the first person to reach the deepest part of the Atlantic Ocean. He traveled to the bottom of the Puerto Rico Trench - 27,480 feet below the surface (8,376 meters) - in a $48 million titanium submarine.
At that depth, any message you send takes 7 seconds to be heard. By comparison, radio waves sent back-and-forth from the moon during the Apollo missions took less than 3 seconds to transmit.
Read more: A $48 million submarine just took a record-breaking dive into the deepest corner of the Atlantic Ocean - 27,840 feet down
Since that first record-breaking dive, Vescovo has successfully completed two other expeditions in the Triton 36000 submarine. On his third dive, at the bottom of the Java Trench in the eastern Indian Ocean, Vescovo discovered a mysterious species that's never been seen by humans.
His final mission as part of the Five Deeps project will be a dive in the Arctic Ocean in September 2019.
The explorer discussed these efforts on Wednesday at the TED 2019 conference in Vancouver, Canada. Here's what he revealed about his death-defying journey.
Hilary Brueck contributed reporting to this story.