Fool's Gold (2008)

An enormous treasure of diamonds, rubies, and emeralds is at the bottom of the ocean, and the recently split-up couple Tess and Ben Finnegan (Matthew McConaughey and Kate Hudson) think they know where it is. Doing research in a dark and cavernous room provides just the spice they need to hook up again. Though that spice also could be attributed to Matthew McConaughey walking or boating around — shirtless or in tie-dye — during every scene. Whatever. Treasure!