Nina Dobrev is turning 36 today -- but she truly doesn't look a day over 20 -- and we've got the photos to prove it.

Check 'em out, people ... Nina is showing off her amazing bod in this series of swimsuit snaps. "The Vampire Diaries" actress strikes many sexy poses in her bikinis and one-piece suits.

For these sizzling photos, Nina has chosen some pretty exotic locations to lounge around ... whether it's on a beach or a sailboat. She even took a few dips in the ocean and drank several cocktails.

Nina is just getting drunk on life. And why shouldn't she? She's one year older ... but who can tell?