From the back cover:
Fortune favors the bold
The world of the Eberron setting holds many wonders beyond the soaring spires of Sharn. Explorers who chase distant horizons might find themselves infiltrating the demon-haunted city of Ashtakala, prowling the jungles of Xen'drik, snatching relics from the City of the Dead, or invading a dragon observatory n the mountains of Argonnessen. The secrets of an entire world are within your reach, but be warned: Glory and peril walk hand in hand, and a journey's end can come sooner than you think!
This book gives players everything they need to explore a variety of sites across Eberron, including modes of travel, exploring tips, and rules for joining organizations such as the prestigious Wayfinder Foundation. For DMs, the book describes several likely "launching pads" and destinations, complete with maps, ready-to-play encounters, and pregenerated MPCs. Explorer's Handbook also provides rules and maps for various modes of transport, including lightning rail coaches and elemental-bound vessels.