This member of the doridina sub-order resembles several other nudibranchs that are commonly found in the Salish Sea. However, its maroon/brown tipped rhinophores and gills set it apart from the Yellow-edged Cadlina,  Cadlina modesta, and Acanthodoris Hudsoni.  It is not uncommon to come across several of these in one snorkel/free dive in the Pender Islands.  They are usually snuggled into crevices in the high subtidal zone feeding on their prey, the ctenostome bryozoan.  As always, Bill Rudham’s Sea Slug Forum site has wonderful links to further information and images, quirks and quarks.  Yes, there are some individuals who are so pale as to almost be missing any darker colouring — and some individuals who are almost a dark grey colour (apparently, a phase).