SAN FRANCISCO (CBS SF) — The sea lions’ occupation of Pier 39’s docks now enters its 24th year of delighting tourists and frustrating fisherman, as marked by a ceremony Monday.

For the anniversary, the Aquarium of the Bay’s has opened a free nature center dedicated to the parade of pinniped-watchers who flock to the wharf.

Now, guests can watch videos, go on naturalist-led tours, and understand the creatures in a more hands-on way.  Pelts and skulls, and a life-size sea lion skeleton are some of the features.

The sea lions mysteriously descended on the area in January 1990, after the Loma Prieta earthquake, and have never left.

“We are excited about this opportunity to continue to share the importance and wonder of San Francisco Bay,” said John Frawley, Aquarium of the Bay CEO. “The Sea Lion Center helps visitors learn about the sea lions at PIER 39, their role in the ecosystem and the steps we can take to protect the sea lions and their habitats.”