Leaving Saturday on my 3rd Alaska Cruise. Holland America will draw an older crowd than most other cruise lines. Therefore, on board they will dress up more. On casual nights, the dress will be country club casual. 1 informal night is sport coat and tie. Formal nights are suit or tux. Daytime and on shore jeans are fine. Alaska is really casual. Just remember, it may rain. And jeans get heavy when wet and dry slowly.