Ever since seeing the movie "Excalibur" as a kid, the image of the Lady of the Lake with the sword Excalibur in the still water made an impact on me. Here's a mashup version with another favorite "sword".
I'm also fond of this Lego version of John Carpenter's The Thing. [link]
*Warning!* Might not be safe to watch with your young daughter about; extreme body horror...with plastic Lego people. Oh, okay, there *is* a couple of cuss words in it but the gore is rather santized compared to the movie.
In the good old days when Marvel made SW comcis there was a storyline from a planet named Iskalon. Issue 74 &75. Iskalon is a waterplanet where Luke used had to use his lightsaber after an explosion underwater, so yes it works fine underwater.
Speaking of the Lady of the Lake, if you get the chance, read Knight Life by Peter David. Quick synopsis; King Arthur comes back and becomes mayor of New York. Imagine the Lady of the Lake giving Arthur Excalibur in Central Park.
Thanks! I just might. If you're interested Bernard Cornwell did a series of three novels that are a very very cool re-telling of the Arthur legend. The three books are: "The Winter King", "Enemy of God" and "Excalibur". Very very awesome series.