Hey Arnold! - Season 3 is excellent tv series from year 1998. I don't watch many tv series online in Adventure category, but this one was amazing. Hey Arnold! - Season 3 gave me a great pleasure from watching it online. Hey Arnold! - Season 3 is one of these tv series that you can watch many times and always find something new, interesting. Hey Arnold! - Season 3 is worth watching online, espacially if you can watch it for free here. I can't say that I'm a big fan of Animation, but I liked it!.