The Alberni Valley Museum is a useful indoor stop, especially if rain has settled in over the inlet. Its collections cover Nuu-chah-nulth art and culture, settler history, logging, fishing, farming, and the photographs that show how quickly the valley changed.
It is not a blockbuster museum, but it gives context to the town around you. Pair it with McLean Mill or the harbourfront rather than treating it as the whole day.