For the US Coast Guard at least, Bigfoot is real -- and is proudly on display here in Key West, on the southernmost tip of the United States.
The hulking monster in question, a sasquatch of the sea, is a 50-foot-long (15-meter) semi-submersible boat built by drug smugglers in the mangroves of Colombia to sneak tons of cocaine toward the United States.
Though it looks like a scaled-up bathtub toy, the grey vessel was built for stealth and marks a milestone in the cat-and-mouse game played by powerful drug cartels and an international force tasked with stopping them.
"At first, there were just grainy photos. No one believed it was real," a US intelligence analyst, who asked that his name not be used, told AFP this week during a tour of the boat, which is now on a military installation.
Reports of "narco-subs" first surfaced in the mid 1990s but it wasn't until 2005 that US authorities started getting specific intel on one of the craft, when the photographs emerged of a strange-looking vessel bobbing low on the water.
Just like purported pictures of wildmen of the woods, those first images were hard to make out, so when US authorities intercepted the boat off the coast of Costa Rica in November 2006, it quickly won its Bigfoot nickname.
Though Bigfoot is not a true submarine, most of its bulk is hidden below the water, making it harder to spot visually and with radar. Its four-man crew had packed 4.2 tons of the drug into the boat's bulbous bow.
Smugglers still mainly use highly maneuverable, open-hulled speed boats called "go fasts" to zip their cargo across the eastern Pacific or Caribbean to Central America or Mexico, but in the decade since Bigfoot's seizure they have refined their marine know-how and are now successfully building true submarines.
One such vessel, captured in Ecuador before it could conduct any missions, was 87 feet long (26.5 meters) and ran on a diesel engine, but could go completely underwater for short spells, when it would be powered by batteries, the analyst said.
Not content with building fully submersible drug boats, the analyst said cartels are likely working on the next step in the smuggling arms race: autonomous underwater vehicles that don't need a crew, are guided by GPS and can stay underwater for almost their entire routes.
"That's the nightmare scenario," he said.
The analyst works for an international taskforce based in Key West, where 15 nations partner with the United States military and Coast Guard to track and intercept drug shipments.
The so-called Joint Interagency Taskforce South (JIATFS) plays a crucial role in breaking up the $88 billion per year cocaine business and stopping other illicit shipments, some of which are used to generate funding for terror groups in countries across the world.
JIATFS tracks drug movements across vast swaths of ocean around Central and South America and successfully intercepts an estimated 25 percent of cocaine shipments.
Countries including France, Britain and the Netherlands are contributing naval vessels to the mission and help seize illicit shipments and arrest crews, some of whom are prosecuted in the United States, while others are sent elsewhere including their home nations in South America.
The penalty for drug running is between seven and 14 years in US federal prison, officials said.
Still, there's no shortage of men willing to spend days at a time on a cramped, dangerous and foul-smelling narco-sub, the analyst said.
The captain of such vessels can earn as much as $75,000 for a single run. Money is plentiful for the cartels -- the boats themselves can cost about $1 million to build, but that is just a tiny fraction of their cargo's value.
Though drug subs are now used routinely, catching additional Bigfoots has proven tricky, as crews scuttle the vessels the moment they are spotted.
"Then they just float around on a dinghy until we pick them up," the analyst said.