Katy Perry Stuns in Black Bikini, Hanging Out With Pals on Yacht After Breakup

Katy Perry's reminding Orlando Bloom what he's missing after their shocking split ... shining as bright as a "Firework" during a yacht trip -- which he was on, too!

The singer-songwriter was spotted wearing barely anything while out on the water on Saturday ... donning a very tiny black bikini and glistening after a dip in the crystal clear ocean.

Her hair's pulled back in a tight bun in the photos, and she's got a pair of dark Hollywood shades on as she laughs and jokes with a couple of friends on the boat.

Perry will certainly get the rumor mill churning ... 'cause she was hugging a dude on deck -- however, we're told this is none other than her close pal, former Hollywood agent Michael Kives. He's married, and there's nothing romantic going on between them.

We're also told venture capitalist Ben Schwerin is on the trip with his family.

Plus, our sources say Orlando was on the boat as well ... though we didn't catch a glimpse of him in these pics.

Perry seems in good spirits amid her ongoing split ... on which she broke her silence earlier this week via her rep.

ICYMI ... Katy and Orlando released a joint statement to Us Weekly, in which they revealed they've slowly gone from romantic to just coparenting -- adding they plan to be "seen together as a family, as their shared priority is -- and always will be -- raising their daughter with love, stability and mutual respect." Given their afternoon around one another, they're clearly living up to the statement.

Orlando was actually in Australia with their daughter to support Katy just last month ... but, the romantic part of their relationship is done for good.

Katy's been touring Down Under in recent weeks ... while Orlando attended the star-studded Jeff Bezos and Lauren Sanchez wedding -- where sources told us he wasn't looking to hook up with anyone.