Ocean park is not that fit to bb under 5 cus it got lots of stairs which can't take stroller. Although bb can walk now, we still need to hold them sometimes.... We went there on the first b-day, and it was a nightmare. Matthew could walk at that time but we still need to use stroller when he needs to take a nap.
I suggest Disneyland...yes, it's small but good for stroller and flat path for bb to walk safely.