hmmm...while poking around looking for Naruto images, I canme across a tour page, offering tours of the Onaruto Bridge, and the whirl pools that form underneath.

After reading the page, it reminded me of the story arc with bridge that was named after Naruto... :-)
Shows where he got the idea, perhaps?

#3. One-day Akashi-Kaikyo Bridge Tour

more whirlpool info

Just little factoids... Enjoy!