The other California: Follow Hollywood stars to Mexico’s vast Baja coast for sunshine, sea and awesome marine life

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Baja California may be the world's third-longest peninsula, but it's largely unknown in Europe. It's just across the U.S.-Mexico border, close to Tijuana and the line of President Trump's contentious wall.

But the vast majority of Baja's resorts are strung along what's known as The Corridor, a 20-mile stretch on the southern tip that connects party central, Cabo San Lucas, to the far more attractive town of San Jose del Cabo, with its missionary church, pretty streets and artisan galleries.

Fun in the sun: Cabo San Lucas, at Baja's southern tip, is the party capital of the region

It is a favourite among Hollywood stars, so holidays here don't come cheap. But, as we are celebrating a special occasion, I've booked us into the aptly named One&Only Palmilla, which my hard-to-please wife instantly judges 'the best hotel we've ever stayed in'.

Breathing a sigh of relief that its exquisite Mexican hacienda-styled rooms, two sandy beaches on the Sea of Cortez (between the 800-mile long peninsula and mainland Mexico), pools, seafront restaurants, spa, friendly staff and gracious lifestyle meet with her all-important endorsement, we head out to explore.

Whale of a time: Marine life - such as humpbacks - and humans love to frolic off the Baja coast

These waters are home to more species of whale and dolphin than anywhere else on earth. And nearly as broad a species of humans choose to holiday here, ranging from squeaky-clean Jennifer Aniston and George Clooney (who used to own a villa nearby, next to Cindy Crawford's) to bad boys such as Sean Penn and Charlie Sheen.

But the real stars of the Baja show are the 350 warm, sunny days a year, the desert landscape and the treasure-filled sea.

The 6,000 ft-deep Sea of Cortez was named 'the aquarium of the world' by Jacques Cousteau because of the sea lions, turtles, whale shark, dolphins and whales that romp here between December and March.

Even in September, when we visit, there's plenty to spot on a day boat trip out to Espiritu Santo, part of a Unesco World Heritage site comprising 244 islands and coastal areas.

The first sign of marine life we spot is a floating plastic Coke bottle. When Jaime, our marine biologist guide, tuts and grabs for it, the bottle darts out of reach, pulled by a 2lb dorado or dolphin fish.

Local men, Jaime explains, use plastic bottles as rods with gut, hooks and bait attached. 'This fish was stronger than the fisherman and got away,' he says.

Unfortunately, it is too bloodied and exhausted to be returned to the sea and finds its final resting place that lunchtime when it is served to us as sashimi sushi on tacos with ceviche (marinated raw fish), guacamole and beer on an idyllic castaway white beach.

The highlight of the boat trip comes at Les Isoles, where we don fins and mask and snorkel through a rainbow of tropical fish guarding an underwater canyon that splits the island in two.

Private playground: The One&Only Palmilla has two sandy beaches on the Sea of Cortez

Across the divide, adult sea lions, some 9ft long, sunbathe on rocks. Fortunately for us, their pups are eager to show off, performing an aquatic dance before accelerating towards us, then veering off to pirouette, belly-up and slip away.

The Mexican dazzle continues on land when we visit our nearest town, San Jose Del Cabo, on the evening of Independence Day.

As we sit in the main square, Plaza Mijares, in the heart of the historic colonial district sipping margaritas, the sunset performs a golden symphony over the two towers of the mission church as a band plays and women in cantilevered, brilliantly coloured dresses dance. When we return several days later, the locals are just as friendly, warm and helpful and confirm what a safe destination San Jose is compared with some other parts of Mexico, now off the tourist map.

Our visit to Cabo San Lucas, at the southernmost end of The Corridor, proves less memorable and we quit its characterless Luxury Avenue Mall and glittering ubiquitous marina in a matter of minutes.

Romantic retreat: The exquisite Mexican hacienda-style resort is perfect for special occasions

Our visit, however, is redeemed by our second boat trip, this time out to Land's End, where the vast Pacific Ocean and the Sea of Cortez meet.

Our skipper, Valentine, points out the heaped golden sands of Lovers' Beach before informing us its sister beach on the Pacific side of the promontory is known as Divorce Beach because 'if a couple swim there, they'll definitely separate because they'll die!' There are dangerous currents and often pounding waves coming in from the ocean.

Spending a week in Baja, it is easy to see why the peninsula has become so popular with honeymooners and LA celebrities. Book your own special anniversary here before the rest of the world catches on.