UPDATE: I recently removed the directions to this spot. Like usual, people are going out here and disrespecting it, pissing off residents, getting injured, littering, etc. BUT, after being given the suggestion to have a fee for directions to help weed out the disrespectful folks, I am going to do just that. If you are interested in giving a donation in trade for directions here or to other spots whose directions I've removed please go to this page for more details.
Lawrence Welk cave is a talus cave, which means it's formed by the spaces between large boulders. Water has washed out the soil between the boulders and left some spaces that form the "cave". You can get to Lawrence Welk cave by walking a couple hundred yards west from the corner of Meadow Glen W Way and Meadow Glen Way W in Hidden Meadows north of Escondido. This Google Map link shows the cave location exactly, you can see the boulders and there's a plastic sewer pipe that runs along the top of them. The map shows a road called "Moss Tree Ln" nearby which isn't actually there but you can walk down the dirt road there to the cave.
The cave is a three dimensional maze and rather complex. Make sure you mark your way in so you can find your way out again. Kids have been lost in there before and had to be rescued, and as I said it's very tight and claustrophobic. I've been in there once before with a group of people and it was scary as hell, I certainly wouldn't want to go down there again. But if you're brave you can easily do it. Just don't go on your own and tell someone where you're going.
Map of Caves:
Mission Basilica San
Diego de Alcala
Ocean Beach Farmers Market
Rum Runners Cave
El Campo Cemetary
La Casa de Machado y Stewart Museum
Old Adobe Chapel
Victorian Village Heritage Park
Kate O Sessions Park
Old Point Loma Lighthouse
Please share your experiences with this location!