Sand is everywhere and gets into everything, Tides rise and fall twice a day, Great whites frequent the Northern coast and will grab things in the shallows. Bears are along some portions near the redwoods but not for you to worry just keep food locked up and put away at night
have fun!
Shark attack video
http://www.youtube.com/watch?v=5ZPhQewYf3c&feature=player_embedded#t=147
Bears on the beach
http://www.youtube.com/watch?v=_gsRXxrTag0&feature=player_embedded