Ariel Winter has thanked her boyfriend for making her the "happiest I could've ever imagined" on their first anniversary.

The 19-year-old actress took to Instagram to gush over Levi Meaden for being an "incredible man", and she shared a picture of the pair embracing at the bottom of a waterfall while wearing swimwear.

She wrote: "Happy 1 year anniversary my love. I'm the luckiest girl in the entire world. Thank you for being the incredible man you are, and for making me the happiest I could've ever imagined. Here's to many, many more. I love you. P.S. your crazy butt is the only one who could ever make me agree to jumping off a cliff at a waterfall soooo yeah. I love you. (sic)"

In the caption for the snap, the 'Modern Family' star revealed she had jumped "off a cliff" before the photo was taken.

Ariel is seen wearing a pink two-piece bikini and has her arms and legs wrapped around Levi, who just has swimming shorts on, while they kiss in the water.

The actress also shared another snap of the pair dressed to impress for a photoshoot in smart attire, and she is seen placing her hands upon his face while gazing into his eyes.

Ariel's latest public declaration of love for Levi comes after the 'Smurfs: The Lost Village' star admitted she falls more in love with her beau every day in a post to mark his 30th birthday in September.

She wrote: "Happy 30th my love... Every single second I spend with you I fall more in love. I couldn't be more grateful to be your partner in crime. You are the most incredible man, and I love you more than absolutely anything. I can't wait to celebrate you... Here's to many, many more birthdays together (sic)"

Levi later thanked Ariel for all the birthday love she had given him.

He wrote: "Amazing birthday thanks to this one!!! Just old movies, us and the dogs. A perfect day!!! (sic)"