Clothes regulations only exist in the dining room at night, although people on HAL usually tend to stay in their dinner clothes for the evening. There are only two formal nights on a 7 night crjise and formal is pretty subjective, a pantsuit, church going clothes, a nice cocktail dress, all can be formal so you don't have to dress to the nines. I personally don't wear jeans, but I've seen them many times on Alaska cruises. Have a great cruise. We're going back for our 8th Alaska cruise this summer.