There are 7 caves along the La Jolla coast. Most of them are accessible only by water, but Sunny Jim’s Cave can be walked to through The Cave Store.
The history of the Cave Store goes like this: Gustav Schultz, in 1902, hired two men to dig out a tunnel down to the cave. (It took 1.5 – 2 years to finish, depending on the information sources I read.) He then charged admission to walk down and see the cave. The original path did not have lights or stairs. The stairs were added in later. The store claims there is 145 steps; however, Will counted 142 (including the ones beginning at the store level).
The store employees said it is still the original foundation for the store, which is pretty cool! It’s a great hidden spot on the coast, so apparently smugglers also made use of the cave many years ago. There is still a charge for admission ($10/adults, $7/kids ages 3-17). You can also book your time online, as reservations are required due to COVID.
I definitely took the stairs slowly, as they were uneven, some slanted to one side, and some were wet from moisture dripping out of the rocks.
Once we entered the cave area, we saw a large sea lion resting on a rock in the cave. He had a fishing hook in his mouth. The store employees said he frequently comes in to the cave. Video: Walking Down the Tunnel to Sunny Jim’s Sea Cave
If you are in the area, I think it is definitely worth the trip to see it!
Other links about the cave/tunnel: Atlas Obscura, La Jolla.com