Claudia Schiffer turned the big 5-5 over the weekend … but she doesn’t look a day over 25, and she’s got the pics to prove it!

The supermodel hopped on Instagram Monday and posted a series of photos showing her in a white one-piece looking hotter than ever!

Check ’em out … Claudia shows off her amazing physique poolside at what appears to be a resort in Greece as she plays the board game backgammon, which is lying on a blanket next to her.

She also strikes various poses in two summer dresses, while displaying various products from Hailey Bieber’s Rhode beauty line.

Claudia writes in the caption, “55 today, so lucky to have a happy and healthy birthday!! 🎉”