Surfline
magazine, former pro-turned-surf instructor Alan Burke said that the native Barbadian was knocked over by a "close-out set" - a wave that closes in from both sides - and "likely hit bottom".
Fellow surfer Nathan Florence, who was one of the surfers who had flown into Barbados to surf Irma's swell, was the first to give him CPR.
"Zander was bleeding, and he wasn't moving. They tried to get him to the beach quickly, which was very difficult," Burke said. "Box by Box is a tough place to get in and out of, even if you have the ability. There's lots of big rocks around, and some stick out of the water."
Burke said Venezia's last words were to fellow surfer Dylan Graves, who he spoke to before catching the fatal wave.
"He told Dylan, 'I just got the best wave of my life!'" Burke said. "Dylan was the last person to speak to Zander. Then that next close-out set came through."
Other surfers spoke to local media about the risk of surfing during severe storms.
"That wave only breaks when you have hurricane swells and it breaks in a different direction, so that swell breaks once in a blue moon. When it is breaking guys go there because it is a beautiful wave, but it is pretty dangerous," veteran surfer Mark Holder told Barbados Today.
"In my 45 years I have never surfed that break; I surf at Soup Bowl and other places around the island but I never surf that break because it is pretty dangerous. The way the waves are coming in today even at Soup Bowl, you have to be on your game. You must know what you are doing because out here is not easy. If you are not a professional, today is a day you should sit down and watch."
Venezia, an Olympic hopeful, won the Rip Curl Grom Search in North Carolina in mid-August, and in April he won the National Scholastic Surfing Association regional championships.
He was expected to represent his home country in the 2020 Olympics, the first Olympics to feature surfing as a sport.
The Barbados newspaper Nation News called Venezia one of the island's most promising junior surfers.
Barbados wasn't in the eye of Irma's storm, but it was left littered with debris after the storm brought high winds and rain to the small island country.
The storm blew the roof off of one home, but the inhabitants of that home were not hurt.
At least 10 people have died in Irma so far.