Nina Dobrev really knows how to work a bikini. On Wednesday, The Vampire Diaries actress put her incredible figure on display as she slipped into a black two-piece in Mexico. Aside from showing off her washboard abs as she did a few exercises in the sand, Nina channeled her inner Baywatch lifeguard as she ran along the water with a friend. On Saturday, the 29-year-old returned to the beach for more fun in the sun, this time sporting in a black one-piece with zippers across the front while posing for pictures with a friend. This isn't the only glimpse Nina has given us a glimpse of her fun-filled vacation. After watching the sunset in a sporty blue bikini, Nina couldn't help but post a fun video on Instagram of her working out with her "squad." Looks like Nina is following the motto "work hard, play hard." Related27 Pictures That Prove...