White-speckled Sea Hares (sometimes called White-spotted or White-ringed) can get quite large, and the six inch (150 mm) reddish-tinged one in these photos looked clearly out of place in the very shallow tide pool where s/he was found.  The very large light brown one, found by S. Caley in less than 2 metres of water, was close to 300 mm or 12″  All others in these photos were under 4 inches or 100mm.  These sea hares are more of a nocturnal species, and thus are not commonly seen. All of these animals were discovered after a storm  or high surf had disturbed their shallow, rocky habitat in the Ma’alaea Harbor and Olowalu areas of Maui.  Check out some more photos and some taxonomic history at Sea Slugs of Hawaii.  If you have found a similar looking (and generally much smaller) species, check out the Aplysia oculifera or Eyed Sea Hare.