About 1.5" long. Thinking juvenile reddish-purple version, however, the rhinophores look kind of like D. venustus (which I have never seen in reddish purple!). Do the 'fronds' get fluffier and more branched as they mature? Finally, the 'dots' (parasite? virus? nudibranch?) - I've seen similar on D. venustus but I do not have enough experience with D. iris to know if all the species in this genus can have them.
This one was found on a floating dock very near the area where "herds" of large/adult D. iris are seen by scuba divers during the early summer months. A boat owner told me she'd seen five of the more visible white versions 'swim' past her boat a few days ago, each about 2-3" long. However, I also found a D. venustus in the same general area.
Table Mountain Ecological Reserve. Easily one of the most beautiful places I've ever been too. We hit the Wildflower display PERFECTLY.