There's a certain freedom that comes with hopping in the car and driving to your vacation destination – especially when you're packing dive gear in the back. It's a setup that begs for the spontaneity of letting the weather, your mood or a coin flip determine the day's destination. And in locales with shore diving, like Monterey, California, Maui, Hawaii, and Vancouver Island, Canada, you can take it hour by hour, hustling to wring six drives from the day, or settle back with just one plunge and a whole lot of R-and-R.

Baja, Mexico

The Sea of Cortez – at around 5 million years old – is the planet's youngest sea, and arguably the most biodiverse, packing 900 fish species and 33 varieties of marine mammals. Of these, California brown sea lions are a given any time of year; the rest, like gray whales and orcas, pass through seasonally.

Most Baja road trips begin at the southernmost tip of the peninsula in Cabo San Lucas, the city with the most infrastructure. From there, it's two hours northeast to Cabo Pulmo, the marine park famous for football-field-size schools of barracuda.

If you head north to La Paz, the capial of Baja California Sur, the biggest draw for divers is a day trip to isla Los Islotes, a colony of 400 never-met-a-stranger sea lions. In fall, it's possible you'll encounter hammerheads. January to March, hop to Magdalena Bay to watch gray whales with their calves. And historically, whale sharks have frequented these waters November to March, but for the past two years, rising water temperatures mean they've been present throughout the year. funbaja.com

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Water Conditions July to November offers the best diving, with water temps in the high 70s and 60 feet of viz in July. A mid-November upwelling cools water temps to the low 60s, and viz drops to around 40 feet.

Get Here You can fly directly to La Paz's Manuel marquez de Leon International Airport, but San Jose del Cabo (SJD) offers more flight choices.

Topside Fun Mid-March to mid-November, tour company Fun Baja offers overnight camping trips to Ensenada Grande Beach on Isla Partida, the island north of Isla Espiritu Santo. It provides campers with tents, solar showers, marine-flushing toilets and chefs. Your part? "You experience nature 24 hours a day," says Fun Baja's Tara Short.

Vancouver Island, Canada

"Wolf eels mate for life, and there are pairs that have been at Tyee Cove for years – they know the local divers, and will come out and play," says Derrick Mackay, head instructor for Nanaimo Dive Outfitters on Vancouver Island, British Columbia. Tyee Cove is popular not only for wold eels, but also for Puget Sound king crabs, grunt sculpin and Pacific octopuses.

Mackay also steers divers to Madrona Point on Nanoose Bay, 22 minutes by car north of Nanaimo, a city on the island's south-eastern side, about one and a half hours from the British Columbia capital of Victoria.

He says of the diving at Madrona Point: "Last summer, divers lost count of how may octopuses they found."

Finish the trip by heading south to Victoria's most popular dive, Ogden Point Breakwater. You'll find a high concentration of all the usual Pacific Northwest players at every depth, from 10 to 80 feet. nanaimodiveoutfitters.ca

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Water Conditions Water temps are in the high 40s in summer, low 40s in winter. Viz can be 100 feet in winter. In summer, temps vary day by day, says Mackay, "but below 20 feet, it's typicaly between 40 to 80 feet."

Get Here Fly in to Victoria directly; or, if you land in Seattle, take the ferry from Port Angeles, Washington.

Topside Fun Mount Benson, on Vancouver Island near Nanaimo, is popular among both mountain bikers and hikers who savor the view of mainland British Columbia.

North Carolina

U-boats and sand tiger sharks: These are the things that draw divers to North Carolina. Oh yeah, and its waters pack freighters, tankers, buoy tenders and myraid other downed vessels.

To start your trip with U-boats, head to Nags Head, where the U-85 and U-701 lie in depths accessible to recreational divers. Half of the intrigue of the U-85 is its story: Its most historically significant artifact – the enigma machine – was salvaged in 2001 and gifted to the Graveyard of the Atlantic Museum in the community of Hatteras. The other half is the ship itself, along with the many 50 mm shells and other artifacts that still lie on the sand at 100 feet.

Another U-boat, the 352, and countless sand tigers await after a three-hour drive south to Morehead City. As for the sharks, the wrecks of the Spar, Aeolus and Papoose offer the greatest chances for encounters. discoverydiving.com

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Water Conditions The dive season in the northern stretch of the Outer Banks is May to October. In early summer, the water is in the mid-70s. Come late summer, the water is nearly 80 degrees F.

Get Here From Nags Head, the Norfolk Airport (ORF) is two hours away; Raleigh (RDU) is three.

Topside Fun It's a short drive north from Nags Head to see the Wright Brothers National Memorial in Kill Devil Hills. Jockey's Ridge State Park, back in Nags Head, is popular among kids of all ages who want to play on sand dunes and watch hang gliders.

Maui, Hawaii

Underwater, the topography of the Aloha State's Valley Isle ranges from craters and bowls to sheer walls and pinnacles, but it's the charismatic fauna, such as green sea turtles, spinner dolphins and monk seals, plus odd endemics, including banded morays and devil scorpionfish, that hold the biggest appeal for divers. Both the west and southern coasts yield much of the same marine life; driving between the two areas only increases the real estate in your logbook.

For convenience and a higher degree of infrastructure, many divers base themselves at the west-coast city of Lahaina. From there, it's easy to reach sites like Cathedrals, a series of lava-formed caverns and pinnacles. Or try a shore dive like Mala Boat Ramp to encounter monk seals, plus sleeping whitetip sharks.

From the southern Kihei area, at sites like Makena Landing, aka Turtle Town, you'll encounter more sharks and turtles, and end near Makena Beach, a caramel-colored stretch of sand favored by locals as a quieter alternative to Waikiki. goscubadivemaui.com

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Water Conditions Winter sees water temperatures drop to the mid-70s; in summer, temps average in the low 80s. On most days, 100 feet of visibility is typical.

Get Here Maui has two airports; Kapalua on the west side is for intrastate flights, whereas Kahului Airport (OGG) receives planes from the mainland and beyond.

Topside Fun Reserve a full day for the Road to hana: It's among the island's most trafficked attractions. This 64-mile stretch snakes along waterfalls, lush mountainsides and turquoise coves.

Florida Keys

The Official Florida Keys Wreck Trek logbook names nine don’t-miss attractions. Start in Key Largo to target the 510-foot USS Spiegel Grove and the 327-foot USCGC Duane, which operator Ocean Divers visits on consecutive days.

And although there’s no guide to the must-see reefs, Rob Haff, owner of Sea Dwellers Dive Center, says these sites alone warrant the journey. “Our biggest asset is marine life,” he says.

And sometimes, the two converge: Cece Roycraft, co-owner of Dive Key West, says its common for goliath grouper to wander in and out of the USNS General Hoyt S. Van- denberg, the Conch Republic’s crown-jewel artificial reef.

oceandivers.com; seadwellers.com; divekeywest.com

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Water Conditions Summer typically has water temperatures near 86 degrees F and viz around 60 feet; in winter, viz drops to 40 feet and water temps to the mid-70s.

Get Here Consider flying in to the Key West International Airport and out of Miami International Airport.

Topside Fun Stop by Key West Legal Rum’s distillery for samples of varieties like Vanilla Brulee Dark and Real Key Lime.

Monterey, California

Monterey is the shore-diving 8 capital of the United States: Within a two-hour drive of the city proper, experienced divers can pack in up to six dips a day at the area’s 50 named sites. Ask Max Seale, sales associate with Aquarius Dive Shop, about that number, and he’ll say it’s infinite. “You could park anywhere along Big Sur (Highway 1) and dive,” he says.

One caveat: If you’re new to Pacific diving or don’t know the area, shop owner James Vincent recommends hiring a guide to start. Otherwise, it’s easy to miss what you came to see: massive kelp forests, sea lions, harbor seals and tons of nudibranchs, like the Hermissenda crassicornis and Spanish shawl varieties.

“A lot of divers drop in at 15 feet and see nothing because they’re not in the right location,” says Vincent.

The opposite is true of just about any dive at Breakwater Cove, one of the country’s best dive sites when it comes to unbeatable odds for marine mammal en- counters. Just be prepared: When a sea lion or harbor seal nips your fin, you’d better tug back.

aquariusdivers.com

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Water Conditions Water temps range from the mid-50s in winter to the high 50s in summer.

Get Here Although Monterey has a regional airport, most people fly in to San Jose or San Francisco; if you book online, the Monterey Shuttle will transport you from either airport to the town for $35 each way from San Jose and $45 each way from San Francisco.

Topside Fun “It’s ironic, but I think the Monterey Bay Aquarium is not to miss,” says Vincent.

South Florida

Hour-long boat rides are unheard of, and dive briefings begin before you've left the dock in South Florida. Standout sites in the Fort Lauderdale area include Aqua Zoo, a unique dive experience created when the hopper barge Sea Emperor was filled with 1,600 tons of concrete culverts and sunk to create an artificial reef. Upon its descent, the barge flipped, and the massive concrete tubes spilled out to form what divers now consider an underwater playground, teeming with schools of large southern rays, clusters of nurse sharks, and friendly goliath grouper. Wreck penetration and depths ranging from 50 to 70 feet make this wreck perfect for divers of all levels. Don't forget your dive light – eels, shy squirrelfish and the occasional lobster lurk just out of sight.

For the second dive of the day, divemaster David Heaney recommends Crab Cove, a section of the outer reef where the north and south ends curl to resemble crab claws, forming coves. "It's some of the best diving down there," he says. "Not many divers know aobut it, so it's still pristine and untouched." – Schyler Cox southfloridadiving.com

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Water Conditions Temps hover in the mid-80s in summer, low 70s in winter. Visibility ranges from 40 to 100 feet, and improves in winter with less algae.

Get Here South Florida Diving Headquarters is on the ICW in Pompano Beach, off A1A – a quick ride from anywhere in the greater Fort Lauderdale area.

Topside Fun Hover over the water instead of under it with fly-boarding (see pic below); stand-up paddle boarding and kayaking are other, tamer options.

Florida and Alabama

You needn't spearfish to appreciate the country's densest population of red snapper, found along the Gulf coast stretch from Orange Beach, Alabama, to Panama City, Florida. In fact, it's perhaps better if you're not a spearfisherman, because then you'll also notice the toadfish.

"We call them mother-in-law fish because they're so ugly," says Kerry Freeland, co-owner of Gulf Coast Dive Pros in Pensacola, Florida. At sites like SS San Pablo – a 315-foot cargo steamer sunk in 1943 – he commonly finds dozens, as well as wrasse, butterflyfish and spadefish, thanks to the decades of growth found on the broken-up wreck.

At some ships, like Alabama's M/V Lulu and Florida's USS Oriskany, you'll likely see a bull, sandbar, dusky or blacktip shark. Says instructor Mike Sumlin for Down Under Dive Shop in Gulf Shores, Alabama, "We have every kind of shark you can think of – you're just not necessarily going to see them all on every dive." florida-divepros.com; downunderdiveshop.com

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Water Conditions Water temperatures in summer climb to 82 degrees F; in winter, the Gulf dips to 66 degrees F. Visibility is roughly 40 feet in summer, and 70 feet in winter.

Get Here Most folks road-trip to the Florida Panhandle and Alabama's Gulf coast, but if you're going to fly, Pensacola International Airport is a good pick.

Topside Fun Drive Florida State Road 30A to cruise the postcard-perfect towns of Santa Rosa Beach and Grayton Beach. Stop at the Local Catch Bar and Grill in Santa Rosa to nose on applewood-smoked seafood dip and seafood pie while listening to live music. Work off the meal with a guided tour or rental from paddle-board manufacturer YOLO, based in Miramar Beach, nine miles west of Santa Rosa.