I’m not sure how to answer that one since it’s pretty relative - no particularly high level of competence is required as long as you can get from one side to the other at a decent pace. And it’s definitely not done in the presence of all other freshman (there’s not even enough space in the room) just the other people taking their test at the same time as you (though I really love imagining the swim-test being conducted like the Roman Coliseum or the Hunger Games or something.)
Cornell’s swim test has a bunch of legends associated with it, although most of them aren’t true:
"The University’s mandatory swim test is a graduation requirement only a few other institutions maintain. According to Al Gantert, who has been Cornell’s director of physical education for nearly thirty years, the most popular tale of the test’s origins—that it was created to satisfy a wealthy donor who lost a child to drowing in Cayuga Lake—isn’t true.
The first Cornell swim test was administered in 1919 by Dorothy Bateman, director of women’s physical education. ‘She believed that knowing how to swim was a necessary skill for proper and educated young ladies,’ says Gantert. Male students didn’t take a swim test until the late 1930s, when it became part of Cornell’s pre-World War II military training program. Even then, it was still tougher for women: proper young Cornell ladies had to complete 100 yards, demonstrating specific strokes, while the gentlemen only had to make it through fifty yards (though they did have to do it naked, since [s]wimsuits weren’t standard at the men’s pool until the early 1970s).”
Via the “Swim test” Cornell Facts entry (original source is the Cornell Alumni Magazine July/August 2007).