Photo: Volunteers aiding Scott Cassell during an emergency equipment malfunction nearly halfway through his 30-mile dive in the Catalina Channel. Credit: Scott McGee.

Sometimes, life's biggest lessons come not when everything goes as planned but when everything goes wrong.

Early Saturday morning, as Discovery News reported last week, undersea explorer Scott Cassell set off  from Catalina Island with two goals. One was to set a long-distance scuba-diving record by traveling 30 miles underwater without surfacing.

The other was to attract sharks with an acoustic device — both to draw attention to the endangered animals and get a sense of how many of them still live off Southern California's coastline.

The day did not go exactly as planned. After about five hours in the water, Cassell experienced a major problem with his equipment and nearly drowned. To avoid death, he came briefly to the surface before going back under again. Battling hypothermia and extreme dehydration, he finished the journey in about 11 hours.

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The other surprise involved the sharks. Despite diving through a notorious great white shark zone, Cassell didn't see a single shark all day. About 20 years ago, Cassell has reported, he often saw as many as 100 sharks during a dive in the area.

According to a press release put out by Cassell's team, advancements in fishing technology and a major rise in demand for shark fin soup have led to a nearly 90 percent drop in the shark population over the last two decades. In the Catalina Channel, about 97 percent of blue sharks have been killed over the same period of time. And around the world, people kill three sharks every second.

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"Sharks are not the villains depicted in films," Cassell said. "They are highly intelligent, emotional and a critical component to our ecosystem and marine world. If we continue to allow for sharks to be viciously hunted and be used for things like shark fin soup, there is no chance that we can save this vital population, which has been in our oceans for more than 5 million years, ensuing a massive trickle down affecting the entire marine ecosystem that will eventually threaten yields of other commercially important species."