The on-again, off-again pair were spotted enjoying each other's company under the South Florida sun ... holding hands, snuggling on lounge chairs, and sharing beverages out of a coconut.

Marcus was also seen chattin' it up with a few other hotties in the area before Larsa arrived -- looking somewhat flirty -- but, take a peek at how he interacted with Pippen once she got to the sand ... it sure seems the spark between the duo has been ignited yet again.

Sources close to Larsa tell TMZ Sports ... the two are not officially boyfriend and girlfriend at the moment -- they're currently just speaking as friends -- but, they are in the process of figuring out how they should move forward.

You'll recall, Larcus has ended a couple times in the last few months ... including in late March, when we were told they had officially decided to move on from each other.

Pippen seemed ready to get her hot-girl summer on, too, in wake of the split, posting a sexy bikini pic earlier this month with the caption, "Gearing up for the summer."

But, it looks like Jordan might be joining her for the warm days from here ... at least, that's the case as of this minute.