Here's why great white sharks can't be held in captivity
Great white sharks are the apex predators of the ocean, save for the killer whale. Nothing can really touch them, and their massive mouths have made them infamous as sources of fear from Jaws to Sharknado. Now, why aren't they in any aquariums? Of course, it would be incredibly cruel to house such a massive fish in an aquarium. Here are the reasons why you'll basically never see a great white shark behind glass.
For one, they tend to swim for hundreds of kilometers over the course of just a few days. They cover an enormous amount of ocean in their daily lives, so much that they aren't really confinable to one specific habitat, like many animals are. Their only home is the ocean - the whole ocean. They move constantly, and tend not to settle in one place.
Additionally, sharks die very frequently and rapidly in captivity. They just can't survive. They get very depressed and refuse to eat, and a depressed great white is nothing to mess with. They get extremely aggressive and even slam their noses against the glass walls. They hate captivity, and they often won't eat food given to them by humans. They are hunters, and if they aren't able to hunt, their bodies shut down and they become melancholic, slowly slipping into death.
They are also wildly expensive, given how voracious their diets are. They hunt, kill and eat anything that is in the tank with them. That means that you have to buy massive amounts of fish constantly, and create a tremendous tank for them to swim in, so big that it's kilometers long, and nothing else can be in there with them. Sounds easy, right?
Finally, and perhaps obviously, they are an absolute pain in the ass to catch and handle. You have to capture a wild great white shark, probably partially by sedating it, and then place it a tank that is absolutely tiny while transporting it to the aquarium. It's highly likely that the shark dies in transit, as creating a large saltwater tank for a great white on the road sounds like a nightmare.
A one-million-gallon tank of water in Monterey Bay Aquarium managed to keep a great white alive for 44 days before she was released. In captivity, she only ate four pounds of fish, which is not nearly enough to sustain a great white. After release, she died in one week. It seems the trauma of captivity lasts long after captivity ends. Harrowing, right?
In summation, massive predatory fish are just too wild and hungry to make it in captivity. They need to hunt and make the whole ocean their oyster - feeding them piles of dead fish in a small area of water makes them depressed, aggressive and potentially suicidal. They do not wish to live when they're held captive, as if their physical bodies simply cannot deal.
I guess shark cage diving will be the only way of hanging out with a great white for the foreseeable future.