BOSTON — You might want a bigger boat, but you probably don't need better odds.

The confirmed return of great white sharks to Cape Cod has rattled some boaters and beachgoers. Yet the chances of an encounter involving a human are infinitesimally small, and the likelihood of an attack resulting in serious injury or death is smaller still.

In 2016, there were 53 unprovoked shark attacks in the U.S. — none fatal — according to the Florida Museum of Natural History's International Shark Attack File. Thirty-two were in Florida; 10 in Hawaii; four in California; three in North Carolina; two in South Carolina; and one each in Texas and Oregon. Worldwide, there were 81 confirmed attacks last year, including four deaths.

Statistically, experts say, you're more likely to be killed by an asteroid than by a shark.

Q: Exactly what odds are we talking about here?

A: They vary, depending on where you are and what you're doing in the water. But the National Aquarium in Baltimore says the odds of being killed by a shark are one in 3.7 million.

You're much more in danger of succumbing to the flu (a one in 63 chance); a car accident (one in 90); a fall (one in 218); a lightning strike (one in 960,000); or even an asteroid (one in 1.6 million). University of Florida shark experts say you're 290 times more likely to die in a boating accident than to suffer a fatal shark attack, and 132 times more likely to drown at the beach.

Q: Are there things we do in the water that increase the risk?

A: Surfers tend to suffer the most attacks. Last year, nearly six in 10 U.S. attacks involved someone engaging in a board sport. Experts say that's probably because surfers spend a lot of time in the "surf zone" where waves are breaking — an area sharks also tend to frequent. They urge bathers and others to avoid places where seals, a favorite prey for white sharks, congregate.

Swimmers and waders accounted for one in three attacks. Snorkelers and people using flotation gear figured into a combined 8.6 percent of all U.S. attacks. Massachusetts' last attack was in 2012, when a white shark bit a bodysurfing man on his legs. Even so, perspective is everything: A 2015 Stanford University study concluded that scuba divers are nearly 7,000 times more likely to be hospitalized for decompression sickness than for shark bites.

Related: Great White Shark Leaps Into Australia Fisherman’s Boat

Q: Where are these great whites, and how many are there?

A: Biologists tracking them in Massachusetts say they've identified 279 individuals over the past three years, most along Cape Cod's outer Atlantic-facing coastline. Increasingly, though, they've been straying into Cape Cod Bay. Earlier this month, an 8-foot-long juvenile nicknamed Cisco, for the popular brewery on Nantucket, was detected in the bay near Barnstable. More are expected in July, August and September — the peak months on the Cape.

There are also great white sharks feeding off Long Island, New York, and the New Jersey shore, including one nicknamed Mary Lee that's gained celebrity status because of its Twitter profile managed by the nonprofit group OCEARCH.

Q: If the odds are so minuscule, why are we so scared of sharks? Is it some kind of primal fear?

A: Gregory Skomal, a shark expert with Massachusetts' Division of Marine Fisheries, thinks so. Humans, he notes, have evolved an acutely tuned sense of survival that alerts us to potential threats.

Despite the fact that any interaction between a person and a shark is highly improbable — particularly a deadly one — "there's a deep-seated fear in all humans of being bitten by some animal, either on land or in the sea," Skomal says. "And the ocean looks dark and deep and foreign to us. It embellishes that fear."