Waterbeds primarily consist of two types, hard-sided beds and soft-sided beds.
A hard-sided waterbed consists of a water-containing mattress inside a rectangular frame of wood resting on a plywood deck that sits on a platform.
A soft-sided waterbed consists of a water-containing mattress inside of a rectangular frame of sturdy foam, zippered inside a fabric casing, which sits on a platform. It looks like a conventional bed and is designed to fit existing bedroom furniture. The platform usually looks like a conventional foundation or box spring, and sits atop a reinforced metal frame.
Early waterbed mattresses, and many inexpensive modern mattresses, have a single water chamber. When the water mass in these “free flow” mattresses is disturbed, significant wave action can be felt, and they need time to stabilize after a disturbance. Later types employed wave-reducing methods, including fiber batting and interconnected water chambers. More expensive “waveless” modern waterbeds have a mixture of air and water chambers, usually interconnected.