Scott Disick and New GF -- 18 Fits Me Just Fine (PHOTOS)

Scott Disick took his new girlfriend across state lines ... from New York to Florida.

Scott and 18-year-old Lindsay Vrckovnik were having fun in the sun in Miami Friday, showing skin, nuzzling and soaking in the sights. Lindsay's got some nasty bruises on her legs.

They spent a day or so in NYC the day before, where Scott showed Lindsay around.