Does it cost if I use my own boat to get to the caverns and walk up to them?

There is still a cost associated with the bus ride and tour of the caverns. We do not allow foot traffic on the 2 mile road from the shoreline to the caverns as it presents a safety hazard due to the buses driving up and down the road. The courtesy dock is free and we allow the use of it with small boats and patio boats. Houseboats may use the shoreline north of the dock to gain access to the bus parking area and small gift store.

I beleive the dock and road going up to the caverns are unavailable to the general public but please contact the lake Shasta caverns tour office

You should call directly because it's a guided tour. I am not a local there so I suggest asking first, it didn't look like any people outside of the tour boat could go there.