Ocean: All but the smallest of these ships are loaded with onboard extras, such as large gyms with classes, swimming pools, a movie theater, and family and kids programs for all ages. You can treat yourself to a massage or facial at the spa before heading to one of the specialty restaurants for dinner. You also have a wide choice of cabin styles, from small interior spaces with no view of the ocean to large balcony suites.
River: A river ship might not have a pool, spa, or fitness center. And if you do get any of these, they will be small, meaning there may be a small plunge pool on the sundeck, or a cabin with a massage table that counts as a spa. Public spaces are limited, with just a main dining room and one lounge or bar area where you also will gather for entertainment — the kind that tends to focus on cultural enrichment.