You could also try a bantu knotout on straightened hair. You could avoid the curling iron step this way. Tutorial:
22-whoissugar's shows you how to do a bangin Bantu knot out (by request) - YouTube
Now, I will say that whoissugar is...not your typical youtube vlogger, but I love her vids and I find her hilarious. Her knotout has a tighter curl, so I would suggest that you make fewer knots to achieve more of a "beachy wave". You don't get a clear picture of the way she puts in her knot, but she isn't doing a two-strand twist--she just literally twists the section of hair until it curls up on itself. Wrap the hair around itself until it forms the "knot" and secure with a bobby pin.