The Sunshine State’s 8,436 miles of shoreline (second only to Alaska) mean almost limitless underwater exploration. Much of the marine life is big: dolphins, sharks, sea turtles and goliath grouper are as common as orange groves, palm trees and roller coasters. What’s attracting them? Besides the wrecks scattered along both coasts, currents serve an endless nutrient buffet — and make diving as swift-moving as a theme-park ride.

Dive Locker: Panama City

Rigid schedules might work for German train conductors and helicopter pilots, but not for easygoing dive operators. PADI Five Star Dive Center Dive Locker’s charters leave on time from the Treasure Island Marina, but because they typically offer one trip per day, they’re allowed flexibility. So when you encounter a pod of bottlenose dolphins while heading to the dive site, grab your snorkel — you’ll soon be in the water with them.

Dolphins are just one of this area’s big-animal attractions. Year-round, manta rays, stingrays and loggerhead turtles are likely sightings. Every July and August, whale sharks often drop by, says shop owner Tony Snow.

Also during summer, divers regularly spot leatherbacks — a little-seen in-water species — while aboard the boat.

“Turtles breed here,” he says of the famous Panhandle sugar-sand beaches. “Sightings are so common on our dives that nobody really mentions them much.”

Today, as we drop in at the Black Bart — the day’s first dive — I’d welcome seeing turtles or mantas but can’t complain when sandbar sharks slowly circle as we kick our way around the wreck. Sunk in 1993, this largely intact, upright 175-foot-long oil field supply ship has been made safe for divers, making entry into the wheelhouse easy even for those with no penetration training. Light pools in from the former windows, illuminating the stairs as we head into the lower compartments before returning to the perimeter. Clouds of snapper and grouper scatter with each passing diver.

During the leisurely surface interval, the crew offers a spread any soccer mom would be proud to bring to practice: Gatorade and Capri Sun, water and an assortment of snacks.

After everyone has had his or her fill , it’s time to dive again, this time at Accokeek, the 195-foot-long Navy tugboat. I’ve been chatting with a guest from Seaside and didn’t realize that everyone else had already begun gearing up.

“Nobody is yelling at you to hurry,” says Snow of the crew’s laid-back nature. “We’re very relaxed but safe. That’s why anyone who dives with us once will always come back.”

Bird’s Underwater Inc.: Crystal River

It’s first light when Capt. Diane Oestreich pilots us toward Three Sisters Springs. We have the water to ourselves, and at this hour, manatees are still waking. Like clockwork, each wintery cold snap sends them scurrying to the warm water, and Florida has just been served a cold front.

Not all local operators offer a 7 a.m. tour, but Bird’s Underwater Tours has been running its on-the-water shop for 24 years — and they know what works. “Manatees are most playful in the morning,” Oestreich said when I was debating the dawn or 11 a.m. tour. “As the day wears on, they leave to feed. If there are lots of big groups, the manatees tire and retreat to their sanctuaries,” where ropes keep swimmers out.

When we reach the springs, the area is as crowded with manatees as a mosh pit with teens. Snorkel gear on, we slip into the water quietly. In one pocket, a few haven’t been roused from sleep yet. Constellations of barnacles dot their tales — each a testament to their leisurely locomotion.

Once awake, they’re friendly. A calf approaches with its mother in tow. They’re curious, which explains their willingness to approach and, sadly, their endangered status. Like friendly Labradors, with a bit of scratch they roll over, presenting their bellies.

Like most of the captains at Bird’s, Oestreich enters the water with us. On a practical level, this allows her team to constantly monitor the conditions. On a personal level, it allows her to make sure guests don’t overlook animals that blend in with the sand and rock. And some guests prefer a bit of guidance when it comes to interacting with these sensitive swimmers. After all, if you’re rising at the crack of dawn, you want the most of every minute, which Oestreich understands. “In-water supervision can make or break a tour.”

Narcosis Scuba Center: Tarpon Springs

It’s rare that modern dive operators follow marine superstitions, but don’t dare board PADI Five Star Dive Center Narcosis Scuba Center’s custom 32-foot Sportcraft boat with a banana in your pocket. Lob it overboard and you’ll be welcomed with open arms — and likely some joking banter. The tight-knit crew is serious about safety and a few charming, quirky beliefs, but they also treat everyone, even first-time visitors, like family.

The morning I board Narcosis II, nobody’s smuggling illicit fruit — after all, we’ve read the waiver online or heard it briefed over the phone. Rather, we’re salivating to dive the trio of wrecks known as Veteran’s Reef. These barges sit in the sand at 40 feet and serve as a goliath grouper family’s estate.

In the water, the biggest surprise is how many fish congregate at the site. Cobia, schools of snapper and flounder speak to the health of the environment wrapped with starfish, anemones and crabs. Off in the grass beds, a handful of green sea turtles busy themselves with bulking up.

Nearby, sponges and soft corals add a patchwork of color to the rocky ledges. Just don’t expect hard coral. That’s another thing owner and captain Joyce French-Hannaseck won’t kid about: ensuring that divers get a good experience — one that lives up to what they imagine.

“It’s important that people see how beautiful the Gulf is, but we want to manage their expectations,” she says. If sea conditions aren’t ideal, she’ll cancel ocean trips, or suggest nearby rivers and springs unaffected by waves.

“I want people to come away knowing that there is great diving in their backyard.”

I’m thankful for her honesty, and the crew’s adherence to superstition — which, in a way, is one more way they show their care and commitment. It all adds up to a better experience, even for those who don’t believe sailor lore. After all, I’m a woman and today is Friday; neither of these things bodes well for boats. And yet, we’ve enjoyed nothing but smooth sailing.

Jupiter Dive Center: Jupiter

The hot drop can inspire dread: Readying every piece of gear in time to hit the water in sync with a group of other divers can be an exercise in timing and preparation.

When I boarded Republic VII, I thought I had no cause for nerves; my gear had been serviced mere weeks ago. And yet seconds after entry, a free-flowing octo begets panic that I will be boat-bound while others cavort with sharks and goliath grouper.

Instead, PADI Five Star Jupiter Dive Center’s Captain Tim Daley scoops me up instantly while divemaster Phil Berg darts to replace my octo with the spare.

Like those responsible for Daytona 500 pit stops, this crew readies me for action in seconds.

And thank goodness. I’d heard nothing but praise for the Tunnels and didn’t want to miss a moment of this famous dive site. The Gulf Stream along this stretch of Florida coastline is as pushy as a trinket peddler on a beach in Mexico. Its speed translates into easy cruising but could quickly prove frustrating if you separate from the group, as I have.

I’m dropped right back in where I need to be and reconnect with my buddy instantly. After a wild exchange of questioning and answering gestures, he points to the sand, his eyes wide. At first I see boulders — then the fins belonging to a pair of 500-pound goliath grouper facing upcurrent. A few fin kicks away, another massive grouper powers under the ledges of a circular overhang, terrorizing the schools of squirrelfish beneath.

Then I see it, another Florida marine life highlight: a loggerhead turtle with a head the size of a volleyball. He’s using his overgrown front fins to amble across the sand. And so passes the rest of the dive: Reef sharks, rays and goliaths eye us curiously as the current push-brooms us along the ocean floor.

The beauty of the drift off Jupiter is that it helps spread any group out a bit more, and the visibility is great enough that you likely won’t lose sight of your dive guide. It’s also more likely that locals — the wildlife — won’t be spooked by possible crowds. You’ll see it all — even if your gear doesn’t.

Destination Primer

Average Water Temp: 60s to 80s depending on location and time of year

What to Wear: 3 mm to 5 mm fullsuit depending on time of year

Average Viz: 50 to 100 feet

When to Go: Year-round