From the publisher's website:
At the far end of Thean civilization lies the Midnight Archipelago - a tropical island chain on the edge of the Great Western Ocean. There, brave explorers chart the lost ruins of alien civilizations, pirates carve personal empires in blood and gold, and hidden jungles hold monstrous beings unseen since the dawn of man. Come venture to the furthest reaches of unknown seas... and see what thrilling adventures await. Includes a complete history and description of the Midnight Archipelago, as well as specific entries on numerous different islands - each one teeming with adventure and suitable for use in any campaign. Fully compatible "hybrid" rules, suitable for BOTH d20 System play and 7th Sea's classic roll-and-keep system.