As underwater archaeology students carefully measured remains of the historic paddlewheeler scattered on the ocean floor off Key Largo, a tiny fish -- a blue-headed wrasse -- defiantly defended its territory.
"This whole experience has been fantastic," diver Reid Harwood of Half Moon Bay, Calif., said later. "We're doing groundbreaking stuff on a wreck that not a lot of people have seen. And there's the wildlife all around."
A field school organized by the nonprofit PAST Foundation, with assistance from the Florida Keys National Marine Sanctuary, spent two weeks doing the most complete survey yet of the Menemon Sanford shipwreck, a 237-foot side-wheel paddle steamship that sank after a December 1862 grounding.
"I love everything about the Sanford," said archaeologist Anne Corscadden Knox, the project's principal investigator. "It's a unique ship with a wonderful story. This is a chance to pull everything together."
Remains of the Menemon Sanford were uncovered in 1989 when the freighter Alec Owen Maitland crashed into the reef, uncovering artifacts about a mile and a half southwest of Carysfort Light.
The site didn't receive much attention until the mid-1990s, when sanctuary volunteer diver Denis Trelewicz and other members of a shipwreck-survey group identified and charted it. Before his death, Trelewicz extensively photographed the wreck and pursued its history.
"On a calm, clear day when absolutely nothing was wrong, the Sanford took a hard right turn and ended up on the reef," Corscadden recounted in the lilting accent of her native Ireland.
At the time, the Sanford carried 800 Union soldiers of the 156th New York Volunteers, part of a flotilla in the Banks Expedition en route to New Orleans. The Sanford, launched in 1854 as a New England coastal steamship, was authorized to carry a maximum of 247 passengers.
No one died in the grounding but a large amount of gear needed for the Union expedition up the Mississippi River was lost.
The Sanford's captain, A.W. Richardson, was arrested and sent to Key West on suspicion of being a Southern sympathizer who grounded as an act of sabotage. What happened to Richardson remains unknown, Corscadden said.
After the remaining fleet reached New Orleans, Gen. Nathaniel Banks sent a dispatch noting "the successful arrival of the flotilla, all but one, the M. Sanford." President Abraham Lincoln received the letter.
Troops taken off the Sanford literally escaped with the clothes on their backs. Their commander later complained of hardships they endured because of their limited supplies.
Salvors soon removed the steamship's large single-piston engine but the wooden hull and two paddlewheels were abandoned at Carysfort. "Wooden wrecks do not fare well on the outer reefs of the Florida Keys," says a PAST report.
Most visible of the Sanford remnants today are broken metal rims of the massive paddlewheels, which may have been 30 feet in diameter.
Nearby on the sandy sea floor lie torn sections of the ship's boiler. Corscadden pointed out to a visiting diver what first appears to be remains of a modern lobster trap. "Boiler fire grate," she wrote on a slate.
A handful of wooden beams, including a structure identified as a large cleat, have survived 136 years in the Keys ocean.
On Wednesday's last dive of the 2008 expedition, Corscadden said, "I was still finding things I had not seen before. There are parts all over the place."
Information compiled by the seven students and a detailed site survey will be used for additional research.
"Which way a bolt went in may tell us how the paddlewheel worked," Corscadden said. "We tell our students that while on the project they will be working for [the National Oceanic and Atmospheric Administration] in a professional capacity. What we find will be turned over to the country."
John Halas, Upper Keys regional manager for the marine sanctuary, said efforts by PAST and other historic-research groups play a valued role in preserving Keys maritime heritage.
"We do not lack for shipwrecks," said Halas. "Part of the sanctuary management plan charges us with preserving cultural resources like shipwrecks but we have limited resources. PAST and the other groups do a great job."
Students, most in college or recent graduates, receive hands-on training and field experience, Corscadden said.
"Underwater archaeology is one of the most intense levels of archaeology," she said. "You have limited time in demanding conditions, and you can't talk to each other. It requires talents that not everybody can do."