LOS ANGELES – One hundred and fifty miles off the coast of Baja California, Mexico, lies Shark Central.
Isla Guadalupe has 22 miles of blue island waters swarming with great white sharks — and tourist boats.
"It's pretty much the only place in the world where you can take a trip and pretty much know that you're going to see sharks," says Martin Graf, president of Graf Diving in San Diego.
To get an up-close look, adventure-seeking passengers are lowered into the crystal-clear waters in shark cages. The crew spreads bloody hunks of bait all around, and then you wait.
Click in the video box to the right to watch a full report by FOX News' Adam Housley.
"You have certain things in life that are on your list of things to do," says eco-tourist Ted Haines, "and being in a cage and watching a great white shark feed was definitely one of them for me."
Customers pay thousands of dollars for the great white thrill ride, but some marine researchers worry there may be serious consequences.
"It is one of the most basic tenets of wildlife care that you do not feed wild animals, because it alters their behavior," explains Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation in Santa Cruz, Calif.
"They begin to lose their natural reticence, indifference, maybe even aversion, to humans and begin to associate them with food, perhaps."
The charter companies say they aren't feeding the sharks, exactly — just luring them to the boats with tuna and sardines.
"Unless they're actually fed, they're not positively re-enforced to come to that cage," saysPeter Klimley, a marine biologist at the University of California, Davis. "In fact, they're, in a sense, what humans may call frustrated."
So the argument is they're only making the sharks mad, not training them to eat human flesh.
"To actually train a shark to, let's say, to associate a boat with feeding, that shark has to appear over and over again, and you have to feed it over and over again," Klimley says. "This generally does not occur."
Research is being conducted to see whether shark tourism is having an effect on the creatures. At least one tour operator says that if it is, he's finished.
"Through this research, we'll be able to determine whether we are having an impact, and if we are, then I know I, for one, will pull out of great white shark diving at Guadalupe Island," vows Greg Grivetto, captain of the Ocean Odyssey, one of the boats run by Horizon Charters in San Diego.
The question is: With a profitable new source of tourism dollars at stake, will anyone else?