I haven't been to Santa Cruz, but generally, you can launch a kayak from any
beach I've been on. You shouldn't have to go to a boat launch. You should be
courteous of swimmers and surfers though. I wouldn't go kayaking at Santa Cruz
because I'm a big chicken and am afraid of the monster surf there. Maybe
someone who has done this will comment.

I'm getting a sea kayak.. can I launch from the beach in Santa Cruz, or can I
only launch at certain points like the yacht harbor?