Waldo is 6 feet tall and weighs 115 pounds. When last seen, he was wearing all yellow.
Family members have searched high and low. They have publicly pleaded for his safe return, even offering a $500 no-questions-asked reward.
If they could put his photo on a milk carton, they would.
But after two weeks of despair, researchers at Sarasota's Mote Marine Laboratory are beginning to lose hope. Waldo, the beloved Red Tide-sniffing robot, may never come home.
"We're kind of at a loss," said Dr. Gary Kirkpatrick, the scientist who named Waldo, built Waldo's Red Tide detector and, for all intents and purposes, is like a father to Waldo.
Waldo, one of Mote's three robots - or autonomous underwater vehicles - disappeared Aug. 31. He was patrolling off the Southwest Florida coast for five days, sending satellite signals and submitting data every two hours or so. He runs on his own, via programmed courses set by the lab, and is equipped with a GPS and several backup communication devices.
But all systems on the $130,000 robot, including his special Red Tide sensor, appear to be dead now.
Mote scientists first learned something was amiss when Waldo reached a point about 11 miles west of Venice and only moved about 100 yards over three hours. He usually moves faster, zig-zagging up and down the water while he works.
"The most likely thing we thought is he had gotten caught on something," Kirkpatrick said. "Like a net or piece of rope. But we have surveyed that area pretty thoroughly and that doesn't seem to be the case."
Other possibilities come to mind. Perhaps Waldo got hit by a boat. Maybe he sprang a leak and sank to the bottom of the gulf.
And then there's this scenario.
"It's possible someone saw him and thought he looked interesting and decided to take him," Kirkpatrick said. "We want people to know, if you've got it sitting in your boat or truck somewhere, we'd sure like to have it back."
Waldo's disappearance should matter to a lot of Floridians, not just the scientists at Mote. He has been on about 40 Red Tide missions since the lab adopted him in 2005.
Red Tide, which kills sea life and causes respiratory irritation in beachgoers, is still somewhat of a mystery. Waldo, equipped with the research device that Kirkpatrick designed and built, collected data and phytoplankton measurements as much as 100 feet deep and 30 miles away from the coast. He was doing the kind of work that humans simply cannot do.
And he was expensive.
"We don't have funds to buy another one," Kirkpatrick said. "It'll take us awhile to recover from this."
Waldo's mission was funded by a grant from the Florida Fish and Wildlife Conservation Commission. His sister and brother underwater robots, Carmen and Nemo, are owned and funded by the National Oceanic and Atmospheric Administration and are not currently in use.
Waldo was originally named by his serial number, 45; then came robots 54 and 55. It quickly became hard to tell them apart, so Kirkpatrick named them after well-known fictional travelers. Carmen after the mysterious and elusive Carmen Sandiego. Nemo after the lovable cartoon fish who sets out on an adventure.
Then there's Waldo: Fun. Familiar. And famously hard to find.
Anyone with information about Waldo's whereabouts can call Mote Marine Laboratory at (941) 388-4441, ext. 271. Emily Nipps can be reached at firstname.lastname@example.org or (727) 893-8452.