I grew up in Knott's backyard, and spent many summer days in the 70s playing ditch 'em with friends on Jungle Island.
It closed October 1, 1982 to make room for a huge parking lot. The "free side," as we called it, included a lake with pedal boats and a steamboat, an antique carousel, and a miniature train. See tinyurl.c*m/57fbxm for the site plan of the Island. (Replace asterisks [*] with lowercase o, due to Flickr's blocking of tinyurl.)
Other good links:
tinyurl.c*m/6gvne2 (Scan of Jungle Island postcard) tinyurl.c*m/68ysuj (Covered Bridge Entrance and Lagoon) tinyurl.c*m/6p66nq (Cordelia K steamboat at the free lake) tinyurl.c*m/6n8jv5 (Miscellaneous Knott's pics) tinyurl.c*m/6ctem9 (More historic Knott's pics)