VIDEO: Young sharks swimming close to shore in Santa Cruz

SANTA CRUZ, Calif. (KGO) -- Young great white sharks are swimming closer to shore in Santa Cruz. Experts say they don't know for sure why, but they believe it has to do with warmer water events that have happened over the last couple of years.

"Big blobs of large, warm water masses kind of moving into the bay," said naturalist Megan Petersen. "We did have an El Nino event recently, too. So it's possible that with those warmer water events, these juvenile white sharks just kind of followed the warmer water."

The warmth makes it easier for them to regulate body temperature, so they can spend more time eating fish in "low-energy mode."

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"I've been referring to it as the shark day spa. They just come and hang out and cruise around in almost a sleep mode." Petersen said.

Experts say it's almost like they're sleeping walking in the shallow waters. "Actually seen them crash into each other a few times. They just bump into each other, then scatter," Petersen said.

The sharks can often be found just a quarter-mile off Aptos between the cement ship at Seacliff State Beach and New Brighton State Beach.

There have been close encounters with kayakers, surfers and tour boats coming to see the sharks. "A lot of times, you get too close to them and they kind of go, 'Oh, you're here' and they leave," said Capt. Ken Stagnaro, who operates the tour boat Velocity out of Santa Cruz Harbor. "But other times, we've had some really good looks, where they'll come right up and do what we call a drive-by."

San Jose firefighter, fisherman and avid marine observer Eric Mailander says he sees at least six to as many as 20 at a time. They're commonly six to 8 feet long and occasionally larger.

At this stage of their development, they're focusing on fish for food, experts say. They will hunt for sea mammals to eat later as they grow and mature.

That's why experts say you shouldn't be scared. "These sharks are not feeding on people. They're curious," Stagnaro said.

With more and more tourists going on boating tours to check out the great whites, the curiosity seems to be mutual.

Click here to learn more about the spike in shark watching tours.