Unfortunately, at the time of writing, no custom underwater housings is available for any Panasonic digital cameras. Some people have suggested that some Ewa Marine housings (bag-style), particularly the D-A (FrankFZ, Steve's Panasonic forum, 26th February 2004) or perhaps the UA or UA-X, might fit the FZ10.
digideep.com looks like a useful site describing underwater digital photography options, but as of March 2004 there are no options listed for the FZ10.