Amazon has a listing called Dungeons & Dragons Ghosts of Saltmarsh Hardcover Book from the Wizards RPG Team which is believed to be the next official D&D adventure book.

Ghosts of Saltmarsh brings classic adventures into fifth edition Dungeons & Dragons. This adventure book combines some of the most popular classic adventures from the first edition of Dungeons & Dragons including the classic “U” series, plus some of the best nautical adventures from the history of Dungeon Magazine: Sinister Secret of Saltmarsh, Danger at Dunwater, Salvage Operation, Isle of the Abbey, The Final Enemy, Tammeraut’s Fate, The Styes.

Ghosts of Salt Marsh includes a variety of seafaring adventures, enough to take characters from level 1 to level 12. This supplement introduces the port town of Saltmarsh, the perfect starting point for a nautical campaign. Each adventure can be played individually, inserted into your ongoing game or combined into a single epic nautical campaign. Dungeon Masters will find rules for ships and sea travel, deck plans for various vessels, an appendix with rules for new and classic monsters, and much more. Dungeons & Dragons is the world’s greatest roleplaying game. Created in 1974, D&D transformed gaming culture by blending traditional fantasy with miniatures and wargaming.

This is in line with what Wizards of the Coast have hinted at – that a nautical element was something they were considering for Dungeons & Dragons 5e and that a remake of the original Saltmarch trilogy was on the cards. We’re lacking full confirmation from WotC and so this product posting on Amazon could well be considered a leak.

The cover depicts a sail ship under assult from a tentacled creature, something like a kracken, but also adventures against a humanoid foe that may well be a sahuagin.

The Sinister Secret of Saltmarsh was originally published in 1981 for AD&D and the Greyhawk campaign setting. The adventure took PCs from level 1 to level 3 and featured a ghostly ship and a mansion haunted by an evil alchemist.