Here is one of my favorite not-to-be-missed spots:
Carlsbad Pipelines surf shop is named after Witt's (the owner) father's plumbing business. It has been in business since 1984. The staff is very helpful and most of all, patient with all the summer tourists! My boys spent hours looking at surfboards and skateboards. The have surf boards for rent and sale as well as a most anything you need at the beach. They have a great selection of sandals and flip flops, which is a big plus. (We inadvertently buried a flip flop in the sand on day 2...ugh)
If you go it is located at 2975 Carlsbad Blvd. Right on the main street just down from The Carlsbad Inn and right next to Coldstone Creamery.