Ocean vs. River
"Water type" is the first fork in the road: cruising the open sea, or cruising a river through the heart of a country. They're different vacations more than they're different versions of the same one.
OCEAN
Ships from boutique yachts (under 200 guests) up to 6,000-guest resort ships, with pools, shows, and many restaurants. Itineraries mix coastal port days with days at sea in between, sailing seas and open water.
RIVER
Small, low-profile ships of roughly 100โ200 guests built to fit under river bridges and dock in town centers. They tie up almost daily, focus on scenery and culture, and fares are usually close to all-inclusive.
River ships cluster tightly in size — they don't vary much by design tier the way ocean ships do — so they get their own bucket in the Ship Size filter instead of being split across the ocean-ship size bands.