We considered cruise to Alaska from Seattle R/T without passports, but our TA advised it was good to have in event of an emergency (ie medical in Victoria, BC). If we had to fly back into US, we would have to have a valid passport. Also, one of the White Pass Railway/coach excursions (train to White Pass Summit, returning via coach rather than train) required a passport to book. Nonetheless, we went ahead and got our passports. Then we’ll have for any future adventures outside the US. Maybe the Caribbean next time.