UCSC competes in Division III of the NCAA as a member of the NAIA's California Pacific Conference.

Before joining the NCAA, UCSC's principal intramural sports were fencing and disc golf (still a Santa Cruz favorite).

UCSC's mascot is the banana slug. In 1981, when the university began participating in NCAA intercollegiate sports, the then-chancellor and some student athletes changed the mascot to the "sea lions," a mascot they considered more dignified and suitable for intercollegiate play. Most students disliked the new mascot and continued to root for the Banana Slugs. In 1986, students overwhelmingly voted to return to the Slugs as UCSC's sole mascot. [12] 

The Banana Slug mascot was celebrated in an unreleased 2003 song by the Austin Lounge Lizards. The Austin Lounge Lizards have often played Santa Cruz, and this is their tribute to their home away from home. This 52 second faux collegiate "Fight Song" creates an entirely new image of the Slugs "leaping toward a dunk...oozing lots of spunk," "zipping through the grass....gonna kick your `expletive deleted'," "...slather you with slime...we win another time." It even includes the requisite crowd participation cheer (as if). This surreal blend of Texas rah-rah and Santa Cruz ironic detachment is now considered the unofficial UCSC fight song.

A favorite trick played on new students is to claim that banana slugs actually smell like bananas (they do not). Another is to convince them to lick a slug (the slime contains a mild anesthetic). Although some students claim the slugs are hard to find, and even go their entire college career without seeing one, during the wet early spring they are hard to avoid just a little ways out in the surrounding woods.

In the 1970s there was a huge wooden labyrinth in the area where College Nine is now, north of the Campus Health Center, an abandoned 'Senior Thesis' project. A popular tradition was to take new students to this maze in the dead of night when the moon was new and have them find the center of the maze in the dark. On the way, the initiated would tell a ghost story about a student who hanged himself center of the maze: "and now...his ghost sometimes appears on moonless nights." While not hazing exactly, some people actually freaked out trying to accomplish this task. The maze was torn down quietly by the administration because it was becoming a hazard, or possibly because of the emotional breakdowns.

A noteworthy annual tradition on campus is "First Rain." Traditionally, during the first autumn rain, students strip down and run the span of the campus nude (nearly a mile), gathering more participants as they pass through each residential college. The run usually begins at Porter College and ends there once again with students congregating in a drum circle.

Another campus tradition is the full moon drum circle. On the eve of every full moon, students congregate in the Upper Meadow to drum or simply relax.