1 adv. — especially British Columbia, Geography
moving further south on Vancouver Island.
Type: 3. Semantic Change — This term, meaning moving southward on an island, has been appropriated to Vancouver Island, the 460-km-long island off British Columbia's West Coast. In this function, it has a long pedigree going back to at least the 1960s (see the 1966 quotation), but most likely earlier.
COD-2 marks the term "Cdn (BC)".
See also: up-island
2 adj. — especially British Columbia, Geography
from a more southern part of Vancouver Island.
Type: 3. Semantic Change — The adjectival function seems to be a much more recent development compared to the adverbial use in meaning 1.