Hayden Panettiere -- Sorry, Wlad ... She's Gonna Be Mad (TMZ TV)

While Hayden Panettiere surfaced in NYC for the first time since having a baby -- her fiance Wladimir Klitschko hit the beach in Miami ... with their four-month-old daughter Kaya.

Only problem is Wlad took his teeny tiny baby girl out in the ocean ... in the middle of some big waves! He better hope Mama Hayden doesn't see this.