unfortunately there are still many "land locked" public lands among those protected lands in california: public lands which are encircled by private lands, with no easement. in the sierra the access situation is generally very good, however there are definitely examples elsewhere which beg the question of what it means to be "public" when it can't be accessed.

for example, although the summit of berryessa peak is on BLM land, the only access is through private land. fortunately one land owner was convinced to allow an easement on a short section of trail to allow the opening of the berryessa peak trail, and access to this peak, but for years it was public and yet off-limits.[1]

on the west side of lake berryessa, cedar roughs wilderness, currently has no access. there are old roads/trails in there which are accessible from private land, but no public easement.

there was an article posted here last year about similar issues surrounding the crazy mountains in montana[2].

[1] https://www.summitpost.org/berryessa-peak/766290 [2] https://www.bloomberg.com/news/features/2017-10-25/this-land...

Yes, there are national parks but if you are not close to one you are out of luck. Go out to the Mojave for example. There are huge areas that are fenced off.