I found this attractive nudibranch in a small cave at Honaunau Bay which I poke into often. This critter was around 2.5 to 3 inches in length which is pretty large for a Hawaiian nudibranch. It was also pretty active, sliding along the cave floor at a pretty good clip for a slug. This is the first one I have ever seen although the guide books don't indicate that it is uncommon.
All photos Copyright 2011 by Barry Fackler