Universal Access Showers
Most showers have a raised or recessed threshold, but such a ledge can cause problems for individuals getting in and out of the shower. Universal access showers have no raised entry, are a great option for people with mobility issues, and still direct water safely down the drain.

Many universal access showers are custom-designed, but there are some shower enclosures—like this one from Kohler—that can be easily installed in your home.  

Walk-In Tubs
Sitting down and swinging your legs over the side of the tub can be a difficult task for stiff joints. A walk-in tub provides a solution for a homeowner who loves a relaxing soak but wants easy access. Walk-in tubs, however, are not widely used in the United States and may be difficult to find. Companies including DCE Bathing Systems, Glamour Baths, and American Walk-In Tubs carry them.