... It is the keels that scare me.
....
Absolutely. In bygone years of more balls and no brains, we dove across the boat channel separating Magic Island and Ala Wai boat harbor/Kaiser's surf spot and were treated to the game of dodging sailboat keels (no sound, deep running) suddenly appearing out of the murk while also worrying about not bumping into stingrays while bellying thru the bottom muck.