Ah, the bunyip. Interesting. Hadn't heard that one, and I've read a lot of weird world myths to my kids. Yep another thing humans have come up with that represent our fears of swamps and the likes. Maybe it's just a bunch of little baby bunyips I'm seeing in that water.
And maybe Excalibur is just waiting for you to take a vacation to a lake in England? Who knows.
There's a few good Bunyip stories getting around, a search will find some and maybe your kids will like them. As for Excalibur...I was in the UK a little while ago and looked, I even went to Tingagel, but no luck. A break couldn't be had...but I'm not the give up type of guy. You know that. 😊