So smitten she forgot sensible walking shoes!

Eva Mendes and new beau Ryan Gosling took a hike together at L.A.'s Griffith Park Observatory on Sunday. For the pair's romantic trek underneath the famed Hollywood sign, down a steep canyon and back to Mendes' home nearby, the actress, 37, wore chunky platform sandals and a loose, blue mini-dress.

Her hunky beau, 30, wore a long-sleeved shirt (with the sleeves rolled up to show off his muscular arms), jeans, and combat boots. (See more pics of Eva and Ryan's hike from PopSugar!)

Currently shooting The Place Beyond the Pines together, Gosling and Mendes debuted their romance earlier this month with a PDA-packed trip (she even fed him!) to Disneyland.

"There's always been a strong chemistry between them," one source explained to Us of the pair. "This was just a matter of time!"

But Mendes probably shouldn't get her hopes up too high. Drive star Gosling recently told UK-based paper The Times that he's still stuck on exes Sandra Bullock and Rachel McAdams. "I had two of the greatest girlfriend of all time. I haven't met anybody who could top them," he admitted of Bullock (who he dated from 2002-2003) and McAdams (who he dated from 2004-2008).

Mendes quietly ended her long-term relationship with producer George Gargurevich over the summer.