The New Zealander held his breath for four minutes and 24 seconds to break his own freediving record at the annual Vertical Blue competition in the Bahamas
on Saturday. He broke that record two days later on Monday, plunging 124 meters -- almost 407 feet -- while holding his breath for four minutes and 34 seconds.
He surpassed his previous mark of 121 meters, which he achieved in another world record dive in April 2011.
Monday's dive marks the 17th world record for Trubridge, 35.
Freediving is an underwater sport where people hold their breath and dive without external breathing devices. In his new record dives, Trubridge dove in free immersion, which involves a diver holding onto a rope during their dive.
There are dangers involved with the extreme sport. In August 2015, the world's best freediver, Natalia Molchanova
, was presumed dead after she failed to surface during a recreational dive in Spain. Her body was never recovered.
"I had a beautiful descent, everything went well with the descent," Trubridge said of his Saturday dive in a video posted to the Vertical Blue website.
But it was during his return to the surface that Trubridge ran into difficulties, describing his ascent as "terrible."
"At that point I was completely out of the headspace that I need to be in for a deep dive," he explained. "With my focus off, I was not in the right head space, not in the place I like to be, to complete my dive with ease or confidence. In fact, as I neared the surface I thought I might have a big blackout at the top."
Luckily Trubridge emerged unscathed, and went on to break another record on Monday.
It was a special occasion for the Trubridge family, with William's father watching his son break a world record for the first time.
"We lived on the ocean on a yacht for 10 years, it was our home and for him the sea was his back garden, it was his playground," David Trubridge said. "So it made sense for him to do this kind of thing."