Endora says she was skin diving in the Bahamas, but she's wearing a wetsuit.
It has long been established that Samantha cannot undo her mother's spells. because she is too strong a witch. Endora says that Carlotta is the most powerful witch ever, therefore Sam should equally be unable to undo her spells. Yet, Sam & Carlotta have a "dressing and undressing" battle over Juke's costume.