GTA: San Andreas is full of legends, and it's got me chasing ghost ships and urban myths like a schoolkid in 2004

In a first-floor flat above San Fierro's Chinatown, the amiable Triad leader Woozie is on the couch, clutching a gamepad. He's busy thrashing CJ Johnson in competitive multiplayer, much to the consternation of our protagonist. "How are you in the water?" Woozie asks, changing the subject. "Can you swim well?"

"No," replies CJ. "I can't." The cutscene is a reflection of the background stat tracking that goes on in GTA: San Andreas—recording the player's weapon skill, driving ability, stamina, muscle, fat, and most pertinently, lung capacity. This moment in particular is notorious among GTA fans, since it demands you raise your underwater swimming skill to 20% before proceeding to the next mission—an oceanic infiltration of a cargo ship which must be completed to see the rest of the game.

Yet if there's something else most fans agree on, it's that they love Woozie. Where the archetypal GTA quest giver yells and postures, Wu Zi Mu brings a relaxed energy that belies his position at the head of a beleaguered crime family. He trusts and supports Carl, defending him from the racially-founded suspicion of fellow Chinatown mobsters. Against a backdrop of backstabbings and revenge plots, he is an oasis of unlikely chill.

This is the man who wants me to practice holding my breath underwater? Then I'm gonna do it. Watch me speed through San Fierro, mount the curb near the famous ferry building, and plunge my ride straight into the deep blue. It's time to dive.

If there's a reason that most players haven't achieved their advanced swimming badge by San Andreas' mid-game, it's because it's boring. The region's sea is large and largely empty. Once the novelty of its colourful fish has worn off, there's none of GTA 5's scuba antics to keep you occupied. Despite this, and perhaps because San Andreas was the first game in the series to make the ocean navigable, it's a reliable source of legends.

One was a Bermuda-Triangle-esque claim that, when players flew out to sea, they would sometimes lose control of their planes, plunging helplessly into the dark water. Another told of an ocean portal, which could be reached by passing straight through the sea bed into Blue Hell—the community's term for the empty area beneath GTA's map. Once there, you'd be teleported to a random spot somewhere in San Andreas, as if flicked away by a grumpy god.

Finally, there were the ghost ships. The strange sightings through the fog, and booming horns that sounded all along the Embarcadero.

These kinds of urban myths might sound silly to a generation brought up with access to comprehensive wikis that can debunk any absurdity in seconds. But San Andreas is a millennial artefact, released during the heyday of forums and magazine guides. Confronted with a wild claim, most players could only measure it against the evidence of their own eyes and the word of pubescent schoolmates, prone to overexcitement or embellishing the truth.

Don't get me wrong, it's a pleasure to be able to pull up the Stardew Valley wiki and find out that pufferfish can be caught on sunny summer days between the hours of 12pm and 4pm. But I grew up in an era when credulity and conjecture were the norm, and part of me still values the sense of wonder that comes from not knowing the true boundaries of a game's world. The attendant mystery and possibility.

Maybe that's why I found myself falling straight back into that headspace while drifting in the San Fierro bay. Upon veering close to a featureless grey tanker, two things happened. First, my Wanted level shot straight to five stars. And second, an achievement popped up: 'Horror of the Santa Maria'. A lifetime of stories about derelict vessels like the Flying Dutchman and Mary Celeste fired in my brain. Memories of the Abysmal Gale in Thief: Deadly Shadows, quarantined by the city guard after coming into port with a crew of mindless zombies. What exactly was the horror of the Santa Maria? I needed to see inside that ship.

The only way aboard was a hatch on its side, accessible via San Fierro's navy base. But even supposing I could reach it, there was no gangway. Luckily, as a GTA veteran, I knew that San Andreas was home to nature's staircase: the ambulance.

Found outside any hospital and reaching speeds of Jesus-Effing-Christ, the ambulance comes equipped with a three-tiered structure. It's an essential aid to San Andreas' stunted mantling system—allowing you to hop from the vehicle's nose, to the roof of its cab, and then onto the high plateau above the patient compartment. From there, you can reach a variety of ledges throughout the map. So long as you've parked up properly.

The latter proved to be the trickiest part of a routine I perfected over several attempts, while spaffing a third of CJ's ill-gotten fortune on armour and AK47 ammo. Have you ever precision parked on uneven ground, at the edge of a concrete precipice, while under fire from the navy's finest? It's a task that most often ends with a splash, and a protagonist riddled with holes like a fish in a barrel. If the fish was an inexperienced swimmer.

Eventually, though, I was in—barely surviving the welcoming party of a dozen black-clad SEALs, none of whom clapped. The ship was stuffed with crates and radar equipment—the stuff of state secrets, for sure. But where was the great cover-up? The next shipment headed for Area 69?

Finally, reluctantly, I consulted Google about the horror of the Santa Maria. As it turns out, the trophy triggers whenever a player takes a dive into deep water. And it refers, in all likelihood, to another hangout in Woozie's flat. In which CJ leans in and offers a personal confession. "Listen man," he says. "When I was a kid, swimming off the Santa Maria, I once got a condom stuck to my face. Horror like that stays with you for life. Believe that."

Sometimes, it feels as if the age of the wiki has left no room for belief. None of the myths or mysteries that used to transport software to the realm of magic. But there is one consolation, and it's this: the ocean portal, somehow and against all odds, is absolutely real.