A longtime shark advocate has published a video showing him surrounded by oceanic blacktip sharks while he calmly discusses why sharks should not be perceived as vicious man-eaters.

"I can feel them bumping my legs below me. They're surrounding me, they're going around me," Skyler Thomas says at the beginning of the footage, captured at Aliwal Shoal in South Africa. "And at any time, obviously, these sharks – these apex predators – can take me out effortlessly. Why aren't they?"

Thomas, who on Thursday uploaded his footage to YouTube, attempts to answer that question while keeping his arms close to his body as large sharks circle and inspect him.

If this seems like a foolish way to deliver a message, it might seem more so given that Thomas' boat crew was chumming with bait to keep the sharks close.

Near the end of the footage a shark appears to lunge toward the diver's face, and Thomas half-flinches.

Skyler Thomas tries to remain calm while being investigated by a blacktip shark.

He wrote Wednesday in his Facebook video description that the shark was merely going after a piece of chum.

Blacktip sharks, which are found in tropical and temperate coastal waters around the world, are not notorious threats but have been implicated in 28 non-fatal attacks, according to the International Shark Attack File.

Blacktips are listed as near-threatened by the International Union for Conservation of Nature.

Because they inhabit coastal waters, they're highly vulnerable to various forms of commercial fishing.

In South Africa, the sharks are among several large marine critters that become entangled in nets designed to make beaches safer for swimmers and surfers.

Thomas told GrindTV that he planned his impromptu shark talk after scuba diving with his crew.

"The dive guide is also very against the shark nets and said, 'Why don’t you say a few things about the sharks while you’re still in the water with them at the surface?' Thomas said. "Then they started throwing bait around me to keep the sharks in the area. So it was unplanned and unscripted."

Thomas added that social media response, for the most part, has been positive.

In early August, Thomas cut his wrist and swam among blacktip sharks to try to prove that blood does not whip the apex predators into a frenzy.

Videos of both endeavors inspired critics to dare Thomas to try similar stunts with great white sharks or tiger sharks and see what happens.

His response: "I'm happy to; they just need to raise funds for the trip."

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