If The Princess Bride were written by Hoid, also known as Wit, it would be something like Tress and the Emerald Sea. The tale begins as many YA fairytales do with Tress setting off to rescue the boy she loves from an evil sorceress. However, since Hoid is our narrator, it loses the feel of a YA book with the first detailed description of the gruesome way people die if they happen to breathe in a spore from the Verdant Sea. Since the Sea is made up of spores instead of water, it's a fairly common fate for those travelling across it. At least the Verdant is the least dangerous of the seas that she must cross to find her love while escaping smugglers, surviving on a pirate ship, and negotiating with a dragon. It's a good thing she makes some friends along the way because all of that is easy compared to facing down an immortal sorceress.
Once again Sanderson has created a unique world. There are twelve moons in a fixed orbit around Lumar and from each of them comes a different kind/color of aether spore. Verdant spores, for instance, sprout into vines when exposed to moisture. While accidental exposure can be deadly the spores are used in a variety of ways. Cannonballs are made with Verdant spores to hold a ship in place, and Zephyr spores create the explosions to fire the cannonballs instead of gunpowder.
In addition to the environmental hazards, Tress encounters several people visiting her world from elsewhere in the Cosmere. Hoid is not only the narrator but also a minor character in the story. He was cursed by the same sorceress that captured Tress' boyfriend Charlie and is currently an idiot madman with truly terrible fashion sense. Not so different from every other time he shows up in Sanderson's Cosmere. There is also Ulaam, a Kandra from Scadriel, (Mistborn), although he currently looks like someone from Sel (Elantris) which makes him appear undead to the people of Lumar. He is Tress' main source of information on many topics, including the aether spores, Hoid, and everything Cosmere. Lots of magic systems from the Cosmere are mentioned in passing. Don't worry if you've forgotten what terms like Awakening or Investiture mean, they are barely mentioned in passing and have no relevance to Tress and her struggles.
This book is about enjoying the journey, which is full of interesting problems Tress must overcome. Sadly, the ending was fairly predictable. Tress is still a solid standalone story despite its many links to the Cosmere. I'd say it would be better without those references, but with Hoid and Ulaam as minor characters some of them are necessary. Some readers will enjoy catching those Easter Egg references and some, like me, will read the book then look up a couple of things on the Coppermind wiki to jog our memory. The book also includes several nice illustrations by Howard Lyon.
Michael Kramer provides the audiobook narration which is apparently available on Libro.fm but not Audible at this time. Tress of the Emerald Sea is currently available in E-book format with physical books to come in a few months. It is one of Sanderson's so-called "secret project" books that were funded on Kickstarter.