Leo DiCaprio Lounging Around with Nina Agdal

Leonardo DiCaprio looks pretty smitten by Nina Agdal, which makes total sense. She's a smoke show SI swimsuit model, after all.

The actor was all smiles hanging out with Nina over the weekend at The Crow's Nest in Montauk, NY. Our witnesses tell us they smoked for a few hours in the lounge area waiting for a table ... before finally heading in for dinner.

Once inside, they sat on the same side of the table and Leo had his arm around her. We're told Nina even got a little something from the gift shop -- a poncho ... cause it was raining.

If ya got all wet, might as well be with Leo ... said a looooooooong list of hot chicks.