Inside cabins with no views at all are typically the smallest, cheapest cabins onboard. They are great options for budget-minded travelers who do not intend to spend a lot of time in their stateroom, or who want to sleep all day in absolute pitch dark. They are less ideal for cruisers prone to seasickness, those who need natural light and groups who require a lot of in-cabin space. Not everyone will be happy in an inside cabin; it is worth upgrading if the lack of light will put a damper on your vacation.
Oceanview cabins: These cabins are like inside cabins but usually have a port hole or window. A window is much more desirable than a porthole because the porthole can be difficult to look through. Windows will vary in size and some cabins will even have full floor to ceiling windows. Most window sizes for oceanview cabins are about 4 feet by 3 feet. Be sure to read the cabin description carefully to determine if there is a different type of window. Windows can not be opened. Expect to pay $150 to $250 a night for an oceanview.
Other pitfalls include service areas adjacent to or above your stateroom; show lounges or bars adjacent to, above or below your stateroom; and self-service launderettes across from your cabin. Other cabins that can be problematic are those that are situated low and at the back (because of their proximity to engine noise, vibration and anchor) or low and forward (because of bow thrusters).
Exception: Carnival has several cabins which are classified as inside cabins but actually have a french glass door which allows light into the room (no balcony, but the door can be opened). Carnival also has some cabins that have a window, but because the window has an obstructed view (that means there is a railing or object in the way) it is listed as an inside cabin. Royal Caribbean has some cabins that have a window but look out over an inside promenade area. These are called "promenade staterooms".