Key West's Navy presence is more in the air than on the sea. But the Navy still has a pier on the island's waterfront and Navy ships sometimes pull in there.
One occasional visitor gets a lot of attention when it's in port. It looks like something out of Waterworld, or Mad Max — a giant metal box floating on the water.
It's actually the U.S. Naval Ship Spearhead.
"It does look a bit like a science project or like a Darth Vader vessel," said Capt. Steven Stacy, the Spearhead's mission commander.
He's not in charge of the ship's actual operation because Spearhead is run by military sea lift command, a civilian outfit. It runs the vessel; Stacy is in charge of the missions and the people who execute them.
Spearhead is a catamaran and its purpose is to move a lot of stuff, very quickly.
"It's got 48,000-horsepower, four engines, Italian beautiful engines," Stacy said. "We can get up and go."
It's also highly maneuverable though it doesn't have a rudder to steer. The four engines are jet engines.
"You can control each jet separately. This vessel can go laterally, step right off like it has a bow thruster. But there is no bow thruster," Stacy said. It can also spin and change its spin point anywhere from the stern to the bow.
"Watching this the first time made no sense to me as a mariner," Stacy said. "But after awhile of being on board I understand that you can spin this around the flight deck up here, or you can spin it around the bow up there. Highly maneuverable vessel [with] very little draft — 12 1/2 feet."
Spearhead's flight deck can land helicopters and it has a massive cargo bay.
"We can carry about a million pounds of cargo into this space," Stacy said. "To put it in simple terms, about 20 homes that are about 2,000 square feet."
One of Stacy's favorite parts of the ship has nothing to do with its operation or its mission. It's the wall where different units that have traveled on the Spearhead leave their patches.
One of them is for the Secret Squirrels. Apparently, that's a real thing.
"It's got an actual picture of a squirrel eating a nut. And it says 'SECRET' across the top of it," Stacy said. "I don't even know who those guys are."
While it's built to carry tanks and helicopters into war zones, Spearhead recently has been used in an operation called Continuing Promise that works with non-governmental organizations like Doctors Without Borders.
"We bring doctors down to do treatment, dental, small surgeries, preventive medicine, vector-borne diseases," Stacy said. "And we work with doctors in those countries, Honduras, Guatemala, Colombia."
In its current mission, Spearhead is also delivering engineers and equipment to drill freshwater wells to serve communities in Honduras and Guatemala where water is now being supplied by tanker trucks.
"For us, executing this mission, it's fun. Putting smiles on people's faces — and that's something you don't often do in the military, especially with what's been going on in Afghanistan and Iraq," Stacy said. "It's much nicer to come down here into the Americas and really help out, you know, solve some problems."
You can see more of Mark Hedden's images of the Spearhead at his website.