Staff at Karlsruhe Zoo said people are queuing up to see two-year-old Zola, who is not only cute, she's also something of a rebel, refusing to play by the rules.
Boats - which are pulled across the lake on a cable - have become popular with many visitors keen to get a glimpse of the naughty seal.
Some have been lucky, but others leave disappointed, as Zola is generally hiding out in a half-hidden corner of the lake.
"We saw all sorts of things, turtles, big carp, but no seal," said one woman after taking a boat ride to spot her.
Zookeeper Irene Schicker-Ney said Zola usually waited for the visitors to leave, before diving into the water and having a swim around her new home. The zoo's gardeners say they have spotted her sleeping in one of the little boats.
Zola escaped from her enclosure about three weeks ago, simply hopping down a drop of about a metre and crossing a pathway to some bushes before slipping into the lake.
"We think it was due to her curiosity," said deputy zoo director Clemens Becker. But it could also be something that most teenagers would understand, suggested Schicker-Ney - hassle with her parents.
Most zoo animals who escape their enclosures end up heading back into them, she said - but in Zola's case, she does not seem to be interested in going home.
Her keepers are thus feeding her where she is - with specially salted fish to compensate for the fact that she is swimming in fresh rather than salt water.
The only risk is that she might lose her natural shyness and allow herself to be approached by visitors - who would be hard-pressed to resist stroking her.
"I wouldn't recommend anyone do that," said Schicker-Ney. "Because they eat raw fish, seals have many bacteria in their mouths. If a snap led to a wound, it would very likely lead to blood poisoning."