The current version of the flying trireme Zaphnora. Unlike the other three black triremes, this one regularly made trans-oceanic voyages for various purposes, as befits her name. The Zaphnora also gave several of the POV characters in The Nine Empires a very harrowing time on multiple occasions. Even when she wasn't preying on airships that ventured too close to the Hub or the Tower of the Eyes, the Zaphnora's very existence gave cause for concern, as her speed enabled many an inconvenience. I'd go into more detail, but I'd rather not say more and ruin the aura of mystery that is meant to surround these four ships.