This is a relatively rare flatworm. At first, I thought it was a Stella’s Flatworm (very common) and unfortunately didn’t take too many photos of it.  It clearly lacks the white spots that dot the Stella’s, but this particular individual had a couple of white spots on its body.  Its tell-tale features, however, are the  rabbit-like pseudotentacles that are tipped in white or grey and the raised and prominent dorsal ridge.  It wasn’t until I had a closer look at the images that I realized it wasn’t the other “Night Flatworm,” Pseudoceros cf. boloo, or the  Stella’s. For more information and photos, see Keoki Stender’s site or John Hoover’s Hawaii Flatworms page.  Found in 1 metre of water,  Makena Landing, Maui.  Approximately 1.5″ or 37mm,