Yes, there are housings that would allow a quick switch from AF to MF, and then by using a focus gear on the lens and a knob on the port, you will be able to manually focus underwater. This often requires the use of a special port that has the focus knob and allows manual focus.
Manual Focus is underwater is an advanced technique which is often used by videographers, or by macro shooters. Using MF for wide angle still photos is very rare and not really worth the effort, since AF works great.
On compacts, there is no problem at all using MF if the camera supports it. The MF is usually controlled by the buttons on the back or by the ring control around the lens, which housings usually support.