After a sunny Thanksgiving day in Key West, Fla., a Manassas couple reboarded their cruise ship and sailed away for Miami, discovering only as their family gathered for dinner at sea that their 20-year-old daughter had failed to return from the shore excursion.

A search involving Florida police and family members has failed to find Rebecca Myers, who planned to spend Thanksgiving vacation with her family before returning this week to prepare for the fall semester's final exams at Virginia Tech.

Florida police are pursuing leads that include a report she might have linked up with a nomadic youth group traveling through the state. Based on that report, the family yesterday began a 10-hour drive from Key West to Ocala National Forest, where some members of the group were heading, possibly with Myers tagging along.

Key West, a colorful resort town at the end of the Florida Keys island chain, was a favorite haunt of Ernest Hemingway and in more recent times has become a popular destination for cruise ships. Police say that they see runaways and transient youths drawn to the carefree, tropical environment but that a disappearance from a cruise ship is unusual.

And Rebecca Myers's family and friends say it's highly uncharacteristic and alarming for the sophomore to disappear and not contact those close to her.

"Rebecca is a free spirit, and it doesn't surprise me she would wander off, but it's not like her to not call," said Laura Sirgany, a childhood friend.

"She has too much going on in her life to not let anyone know what's up," she said.

Myers is studying urban planning and development at Virginia Tech in Blacksburg and is a member of the women's varsity rowing team. Dave Schuster, her rowing coach, described her as "responsible" and said she is one of his most dedicated athletes.

"She always came to practice, she learned quickly and she encouraged others to do well," he said.

Myers recently had mended family relationships that once were scathed by adolescent pranks and rebellious acts, Sirgany said. "She just seemed really excited about the family trip, and she really wanted to spend time with her sister," she said. "I just can't see why she would do this. I want her to call someone to say she's okay."

Myers's parents, Scott and Elaine Myers, had taken Rebecca Myers, her 12-year-old sister, Sarah, and her paternal grandmother for a four-day holiday cruise aboard the Sovereign of the Seas, out of Miami.

When the cruise ship arrived for the day at Key West on Thanksgiving morning, the family began a tour of the resort town. Scott and Elaine Myers were walking slowly, savoring the sites, while Rebecca and Sarah would take two steps forward, linger and then take two steps back to file in with their parents.

The four finally decided to split up, with the daughters going their own way, but all planning to meet at noon for lunch, the parents said. Only Sarah arrived, saying her sister had grown tired and wandered off toward the beach to take a nap. No one thought twice about it, or became concerned.

"We didn't think much of it at lunch, and we weren't real worried," Elaine Myers said. "She's 20 years old and can be on her own."

They didn't see her on the way back to the cruise ship.

"There were so many shuttles going to and from the ship that we just figured she had found her own way back," her mother said. "But when she didn't show up for dinner, we panicked."

When the ship reached Miami, the family flew back home to Manassas, then drove down to Key West, arriving Sunday evening to begin their search.

Al Citelli, the lead detective on the case for the Key West Police Department, said that investigators don't know what has become of Rebecca Myers but that he is pursuing the tips from members of the Rainbow People that they saw a young woman matching her description get into a car with some other members of the group heading north for Ocala.

Rebecca Myers is 5 feet 7 and 140 pounds and has blondish-red hair, nose rings, multiple ear piercings and a tattoo of a twisted rope on her back. When last seen by her family, she was wearing blue cargo pants and carrying a green backpack. Anyone with information is asked to call the Key West Police Department at 305-294-2511.

"She was ready for her semester finals, and she'd already bought Christmas presents," Elaine Myers said. "Those aren't the signs of someone who would want to just leave."