If you're looking for a good, quick beach read, allow me to introduce you to the world of young adult novels.
Some are insanely bad. They are either badly written, have bad plot development, or the main characters you just don't respect or like. But there are so many really good ones. Here are my top ones that I've enjoyed...
Angus, Thongs, and Full Frontal Snogging by Louise Rennison - There are 10 books in this series and they are AMAZING. It's the diary of a teenage girl in the throes of, well, teenagerdom. Georgia Nicholson is a self-absorbed, marvy British girl who discusses, among many things, the state of her humongous nose, the Sex God, her hilarious 3-year-old sister Libby, and her "insane" parents. Georgia's side-splitting trials and tribulations are not to be missed. It's a light, quick read and I'm sure you will want to read the next ones after you've read the first. These books are perfect for an afternoon at the beach. (The next books include: On the Bright Side, I'm now the Girlfriend of a Sex God, Knocked out by my Nunga Nungas, Dancing in my Nuddy Pants and many more).
Vegan, Virgin, Valentine by Carolyn Mackler - I read this book when I was in high school, but it still ranks high on my list even though it's been a while. High-schooler Mara Valentine has everything in her life under control: good grades, vegan lifestyle, and excellent rapport with her parents. That is, until her cousin comes to visit who is everything that Mara is not. Life for Mara spins out of control - until she realizes that maybe that's exactly what she needed. It's a great read and also quick - another good beach read!
Danny, Champion of the World - Okay, so this isn't a young adult novel, but it's still INCREDIBLE. It's for a little younger audience, but adults will enjoy it, too. It follows the story of Danny, who lives with his father, who is a mechanic, but secretly enjoys poaching in nearby woods. I can't give any more away as it's a beauty to be uncovered all on one's own.
The Hunger Games by Suzanne Collins - So this one obviously is great - and everyone has their own opinions about it. I think the first one is better than the next two and if you haven't read it, give it a try. It's a difficult premise to face, but dystopian lit for young adults is just out of control right now and this is one that stands out among the others I've tried to read. See if you like it and let me know your thoughts.
These are just a few to get you started - let me know how you feel about them!